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4,835 | Is there data available (besides crawling thousands of questions) on how often we use the downvote button, and how quickly? The motivation for this question is Carlo Beenakker's recent answer on MOM. I agree instinctually that downvoting is close to the soul of the 'unwelcomeness' spoken about regarding MO, but I'm curious if these instincts are borne out in the data. Ideally the data set would list downvotes 'per-capita', meaning that sites with higher traffic wouldn't be exaggerated in standing by the naturally higher number of aggregate downvotes, but aggregate data together with traffic data could obviously be used to reconstruct a per-capita view of things. | We can use the Data Explorer to see how often we up- and downvote. This query compares the number of posts (including deleted ones) and the number of up- and downvotes for all sites in the network. On MathOverflow, a post receives (on average) 5.29 upvotes and 0.46 downvotes. Of the 176 sites in the network, we're #23 when it comes to upvotes per post, and #35 for downvotes. We can't use SEDE to measure how fast we downvote; see Why is vote time missing in the SE data dump and SEDE? for details. | {
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4,853 | To quote an answer to a recent meta.MO question: Here are some examples of people we would like the site to be
welcoming to: Prominent mathematicians who are less "online" than the typical MO user. Current advanced graduate students. Currently MO has a pretty bad reputation with both such groups. In
neither case is this primarily about the relationship with math.SE
Certainly the reputation of the site among graduate students in my
department is that MO is too intimidating for them to use. (It's not entirely clear to me what we can do about this reputation or
exactly where it's coming from, but that's an entirely separate
question.) This is that separate question. How can we change the reputation of MO amongst "advanced grad students"? Some recent discussion: Should graduate students be encouraged to participate in MO? If so, at what stage? | I'll go against my best judgement and will reply to this with my own perception. First of all, the best thing would be to ask graduate students directly. I don't know if there are any active efforts of trying to understand the phenomenon you describe, I don't know who would have to run such efforts in any case. But the thing is that what I've seen so far in these meta discussions is that it's mostly hardcore users discussing the merits of the community, this is bound to happend of course, but it's a bit hard to deduce why people don't stick around when you only poll the ones that did. Now my own personal take as an 'advanced' grad student, whatever that means. I reiterate this is why I personally barely ever participate even if Ive visited the site almost daily for the past few years. It takes a lot for me to produce any input. First of all, the format itself almost forces one to a particular style of conversation. The format, the moderation and the vibe itself of the site makes it hard to deviate into having an organic conversation between many people. It hard to go even so slightly off-topic. If I, as a student read an answer that I find relevant to my interests but that I don't understand fully although I know I would with a little bit of help to fill some gaps, it is a bit hard to hop in the conversation and interrupt the almost linear format of the comments to ask for clarification. I can't hijack a comment thread to make it about my own lack of understanding. Which leads me to my second point. Asking a question in an open forum is not a conversation with coffee and snacks after a seminar, nor is it raising your hand after a talk. It's getting up on stage and facing the crowd. It's daunting and I believe it is natural that for most people just trying to break inside the mathematical community to be reluctant to post their questions in a forum like this. Some people can shake off saying something silly here years ago, but a lot would see it as a risk with negatives outweighing the positives. Of course one could post anonymously, but I believe this is discouraged here. I believe this is a factor anyway. I would've loved to post this from a fully anonymous account, for example. On the topic of the questions themselves. It is a struggle itself to come up with good question, not to mention having the skills to make a dent on them. If I'm barely getting by with the work I do, it's a bit of a risk to give away a good question or partial work away for somebody to solve a couple-months-project in a few -sometimes- non even that illuminating paragraphs. I've seen people asking bits and pieces of the questions I plan for my thesis and it's pretty stressing. This is perhaps a very unscientific attitude to have, but at the end of the day it's a fierce competition, sadly. Often people try to conceal their questions by trying to abstract away the context, but this often leads to a poor question or poor answers that understandably miss the point. Last but not least, and a bit of a summary of the previous points, is that the site has a reputation already. People here sometimes try to reason that the attitudes that resulted in this reputation have been mostly eradicated since the early days of the site, but when I google a question and I arrive to a 10 year old post and see somebody being a bit condescending or a bit rash with their answers then my perception is there. Nobody ever explicitly told me about the reputation of the site but it is true that most of the grad students Ive met through the years and institutions don't have a good look on the site, thinking of it as too intimidating in the better cases to outright unhelpful and aggressive in the worst. While it is maybe true that the community is overall kinder in more recent times there's still the odd comment that is not very helpful (not necessarily rude, or mean) with the reputation. I know there are plenty of (ex)grad students who (were)are very active and thrived just fine, so it's certainly possible to be a part of the community at this stage of one's training. But for me and maybe others it just feels like it's not worth it most of the time. Maybe the community should decide if it's willing to make changes to attract more 'advanced' graduate students, or if its goals are in conflict with what people staying out would want to see. | {
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5,033 | This question is about suppression of threads of comments by moderators , moved to chat with the message " Comments are not for extended discussion; this conversation has been moved to chat ", with link to the chat. A recent example is this post . I'm not addressing the case of polemical comments or disputes moved to chat such as this question , or deleted. My impression before the moderator election is that this has been done quite too often on MathStackExchange, and was quite happy that this kind of moderation is performed... with moderation (only with very large number of comments, selective choice of comments moved to chat). I find the comments as being part of the MathOverflow reading. Is a more severe way of acting really needed? What are reasonable criteria to move a comment conversation to chat? In the above example, first there is visibly a problem with the question in view of the vote balance, and, second, reading comments (now moved to chat) is instructive. I would really see a severe streamline of the chat conversations as a deterioration of the site. | Vote up this answer if you think the instrument of moving a comment thread to chat
should be used along the lines of Todd Trimble's comment -- i.e. only if a discussion
in comments goes off-topic or becomes contentious.
(Vote down if you don't think so, and leave alone if you don't care.) | {
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5,182 | I think that the history of this question about connections is unfortunate. I would like to discuss (respectfully, without throwing blame around) whether/how a better outcome might have been achieved. OP asked, as their first interaction with MO, a clear, well-posed question about connections in differential geometry. I think that if you looked in the right graduate-level textbook you could find an answer, but also that you could easily look in several relevant graduate-level textbooks without finding an answer. In the light of 2., I think that the question could have been asked at MSE, but that it is also perfectly acceptable at MO. (The level seems comparable to A and B , which are currently on the front page at MSE, for example.) The question has 4 upvotes, and there is an accepted answer with 5 upvotes, which seems to me to be clear and helpful. There were also two votes to close, with one comment suggesting (along with a typographical correction) that the question was "not research level" and therefore better suited to MSE. I don't agree with that comment, and I do not think that it is consistent with the guidelines to be considerate and welcoming to new users. However, I would accept that this is a matter of judgement. OP was very offended by the comment about MSE. They stated (in a now deleted comment) that they are a tenured academic giving graduate level lectures on differential geometry, and that it was rude to suggest that their question should be migrated to a "site for helping undergraduates to cheat". They reiterated this view of MSE in another comment that has also been deleted (apparently by a moderator). I think that most of us would agree that OP's opinion of MSE is inaccurate, and disparaging to many MSE users who we respect (including many people who are active on both MO and MSE). However, it is not hard to imagine how someone might form that opinion; ideally it would be corrected by exposure to more information. While OP's feeling of offense is clearly enhanced by their low opinion of MSE, I think that it is natural to be somewhat upset at the suggestion that a clear, well-posed, graduate level question needs to be migrated. If people feel a need to make such a suggestion, I would hope that they could do so respectfully and with more explanation. So OP got an answer to their question, but it seems that they did not enjoy the experience, and are unlikely to return. I find that result disappointing. | I just want to comment, I think at this point, fighting and unpleasantness about whether questions are appropriate is a much bigger problem for the site than the presence of less-advanced questions on the site. So, I think one way for this unpleasantness to be avoided is for people to just be a little more openminded about what’s an appropriate question for this site. The site will not collapse because you didn’t migrate a borderline question; it well could if we make life unpleasant for all new users. | {
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5,209 | Right now it seems that a bug is affecting MO: reputation and badges are no longer displayed next to the users' names. This happens both on the front page: as well as on pages of individual questions: Furthermore, the reputation pop-up is also not displayed when I hover the mouse cursor above a user's name. This seems to be a MO-only bug, since it doesn't manifest itself on the other SE sites of which I am a user. This also doesn't manifest itself on Meta. | This is not a mistake. It’s an intentional change to the site that the board and moderators agreed on. We coordinated poorly and did not have a formal announcement ready when the change rolled out; apologies to those who are confused. However, given that the whole point is to minimize attention to points as a feature of the site, drawing a lot of attention to the change would have been self-defeating. | {
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5,531 | The user (or a bot) https://mathoverflow.net/users/496085/canvas123 appears to be posting ChatGPT-generated text on MathOverflow. Two “answers” by this user already got accepted (!): When is a subspace of the cohomology of a smooth projective scheme on $k$ a motive? Can we get that $ P(N^{2/3}(\lambda_N-\lambda_{N-1})\le c)\ge 1-\epsilon$? The question Does every monoidal abelian category admit an exact, lax monoidal functor to abelian groups? has an answer by this user with all the telltale signs of being computed-generated. In particular, the “commutative diagrams” are nonsensical, and the poster is “unaware” of this. | It's worth having a discussion about AI-generated content. At this point, the conclusions of such a discussion are pretty clear: the current state of the art in AI-generated MathOverflow answers is complete garbage. Not only that, but the possibility invites abusing the site by serially posting low-quality and plagiarized content, and in a way which is particularly prone to wasting everybody's time. In principle, AI-generated content may one day be capable of adding value to the site, but that day is not today. If that day comes, appropriate attribution of AI-generated content will certainly be required. In the present, please refrain from wasting people's time. | {
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963 | This is a Canonical Question about the privacy of Server Fault and the needed detail to get an answer from the community. Is there any information other than a password that would be considered a security threat? I am primarily interested in knowing what could compromise the security of a server, rather than the security of intellectual property. For example, it seems to me that it would be a security threat to include both my username and domain name. If I post a large amount of output, it is not possible for me to know what nefarious uses it could be put to, especially if data were combined from across multiple posts. | Provide as much information as necessary to answer the question. You may obfuscate anything that may be sensitive, but be careful of obfuscating too much. These may occasionally come into conflict... Server Fault does not require you to obfuscate anything. These guidelines are intended to keep you out of trouble and to help you get better answers to your questions. Passwords Never post passwords, API keys, or any other credential that can be used for authentication or authorization. If you accidentally post such data, do the following: Consider the credentials compromised and have them revoked or changed immediately. Do not skip this step! API users may retrieve the original revision of your post before you are able to edit it, and your password may then be out on the Internet forever. Edit the post, removing the credentials and other sensitive information. Flag the post for moderator attention. Moderators can then redact the sensitive information from the post's revision history. User names If the content of the user name is itself sensitive, consider replacing it with something generic. Host names and domain names If your domain name is sensitive, replace it with an example domain name. The example domain names are specified in RFC 6761, section 6.5 : example.com example.net example.org example TLD and any subdomain thereof When referring to Microsoft products, it may also be acceptable to use Microsoft's example domain names, contoso.com and fabrikam.com . Never replace your domain name with a domain name which does not belong to you or your organization and which is not reserved for use in examples. NB : In many cases it may be necessary to know the actual domain name in order to answer your question. This is especially true if your question relates to setting up or reconfiguring the domain name itself. An experienced community member will typically comment on your question if this is the case. IP addresses Never obfuscate private IP addresses. This only leads to confusion and makes it more difficult to answer your question. Private IP addresses are those defined in various RFCs: 10.0.0.0/8 , 172.16.0.0/12 , 192.168.0.0/16 defined in RFC 1918 100.64.0.0/10 defined in RFC 6598 fc00::/7 defined in RFC 4193 You may obfuscate public (globally routable) IP addresses, if doing so you must use an IP address range reserved for that purpose (see below). Never obfuscate using IP addresses not controlled by you or your organization and which are not reserved for use in examples or documentation. The following IP address ranges can be used for obfuscation, examples, and documentation. These should be used only to obfuscate public IP addresses: 192.0.2.0/24 , 198.51.100.0/24 , 203.0.113.0/24 defined in RFC 5737 2001:db8::/32 defined in RFC 3849 NB : In some cases it may be necessary to know the actual public IP address(es) in order to answer your question. An experienced community member will typically comment on your question if this is the case. Service providers If your question involves resources purchased or leased from a third party service provider, do mention the names of the providers involved. Many such providers have their own idiosyncrasies and this information makes it possible to answer your question in these cases. Business information When asking questions, do not mention the name of your company unless it is necessary to understanding the question. When answering questions, do mention the name of your company if you are recommending or advising regarding your company's product or service. You are required to disclose your affiliation if one does or appears to exist. | {
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973 | I'm seeing SO MANY questions like this: How to get my server viewable from the internet? From the FAQ: Server Fault is for system administrators and IT professionals, people who manage or maintain computers in a professional capacity. Frankly I'm wondering if we're not being hard enough on these sorts of questions. I would be very shocked to find out that anyone who works in IT professionally can't do a simple port forward, even if their expertise is in something else. That particular question is just attracting poor answers, which will most likely attract more poor questions and more poor answers. Should we be coming down harder on these questions? I'm not complaining that they're simple, or easy to google, or even a bad question - they're just questions that no competant IT person would ask, or if they did ask, they would know to provide more information about their situation. | My suspicion is that this is working as intended. I feel that the entry-level questions are good practice for people new to the field to answer. If a question is relevant to SF, but completely uninteresting to me personally, I simply won't answer it - if NOBODY finds it interesting enough to answer, then the system has worked perfectly and the question will die a natural death. I'm not sure it benefits anybody to vote to close questions simply because the asker doesn't know enough to post the correct terminology. Once upon a time, I'd never heard of an A record, either - but I'd been a professional in the field for a few years before I'd had cause to learn. Somtimes the career path is a winding one. Also, their "uninteresting" nature makes them accessible to lower-rep members to rack up some points on questions that will be passed up by the rest of the community. I'd imagine that otherwise, there's bound to be a lot of frustration for someone trying to build up rep, when every question has a good answer already. | {
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1,039 | "Do you haz teh codez?" is an intentionally misspelled, poor grammar, version of the question: "Do you have the [source] code?". It is written in the style of an Internet meme called lolcatz . In this particular case, the phrase is meant to be considered humorous. Origins of "teh codez" version of this meme may be a direct result of this TDWTF article . Similar phrasing can also be associated with a mocking, or disapproving, tone when directed at [inadequate] requests for assistance from inexperienced users. See also: n00b . | {
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1,330 | Should questions about SQL (the language, not the server) be asked on SF or SO? There are a reasonable number of questions about SQL already on SF but before posing any myself (quite possible due to the project I'm working on) I'd like to find out what others think is the appropriate site to ask such questions. I personally see them as more SO than SF, although the people over there may well disagree. On the other hand, I like the SF community much more and would therefore prefer to ask here. | The way I see it: - SQL language questions belong on StackOverflow - Database server questions belong on ServerFault - Database tuning questions belong on dba.SE | {
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1,332 | First: The question has been moved to superuser. In my opinion it should have been moved to serverfault. What can I do? Second: I try to answer questions on iptables/netfilter. I end up answering questions on unix.stackexchange.com, serverfault.com, stackoverflow.com and now even superuser.com. It is very cumbersome since I've just started and I am missing reputation to do simple tasks. What site do these questions really belong to and can I have them moved to that site? Of course sometimes I answer with a netfilter-solution where it wasn't clear that this can be a solution. These question can stay where they are and so they can be answered using other solutions. | The way I see it: - SQL language questions belong on StackOverflow - Database server questions belong on ServerFault - Database tuning questions belong on dba.SE | {
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1,886 | This is about those two questions: httpd.conf match absolute file PHP 5.3 Not Logging Both had no answer (neither accepted nor unaccepted).
Both askers answered it without actually writing an answer, but by adding a comment explaining the answer editing the question to contain the answer Unfortunately, both did not respond to the hints to create and accept an answer. In one, I added the asker's question as answer because he didn't do that. Now my questions: Is that ok? If not, what should we do in such cases? | Steal comments that answer the question and post them as an answer. If it happens enough either the misguided commentators will be annoyed enough at the "lost" rep to give outright answers next time, or no one will notice / care and you'll help the community and... oh yeah, get some rep. BTW, I stole this answer from Jeff Atwood's comment on sysadmin1138's post, so you should upvote this to annoy Jeff. As Nixphoe points out in the comments below, sometimes you have to lead the author along to get more information out of him. In those cases, comments should be avoided like the plague and any information discovered in comments should be placed in either the original question or in an answer. If you post an answer based on limited information, wait to see if more info is given and then edit the answer accordingly. It's also nice to modify the original question to include all information that is garnered in the process. Throughout all of it, encourage the author to update their own question and provide more information. Eventually people will get the hang of it. The Q/A nature of the site is defeated if half of the pertinent information is in comments, and the accepted answer is only truly acceptable after reading two dozen comments strung out over the question and three different answers. Always under all circumstances strive to keep all infromation in either the Q or the A. | {
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1,986 | We've created, appointed, or otherwise identified certain question/answer pairs that are the canonical answer for certain problems. These are answers where the community has said all it is going to say on a class of subject, because although everyone's particular problems in that class are somewhat different, to the extent that they are interesting, they aren't different, and to the extent that they're different, they aren't interesting (to anyone save the questioner). So we write one answer that's designed to be the last word on the subject, and say no more. A list of these problems is given in the accepted answer below. Please: Post an Answer to nominate a question for inclusion. Questions explicitly posted for the purpose of creating a canonical Question/Answer can skip this. Delete content that has been merged into the official list. Try to keep this post neat and tidy. | These are the questions we have identified as Canonical: Capacity Planning Generic Capacity Planning: Can you help me with my capacity planning? How do you do load testing and capacity planning for databases? How do you do load testing and capacity planning for web sites? Career Starting out: What a beginner should know/learn for sysadmin job? Databases InnoDB: Fatal error: cannot allocate memory for the buffer pool Datacenter Design What's the best fire suppression for a server room? Server room survival kit? What were your server room pain points, big wins and must haves? What to look for in a datacentre ethernet switch Documentation Getting started with documentation EMail & Spam How to stop people from using my domain to send spam? What are SPF records, and how do I configure them? Fighting Spam - What can I do as an: Email Administrator, Domain Owner, or User? Prevent mail being marked as spam How to send emails and avoid them being classified as spam? Hardware Why is Enterprise Storage so expensive? What are the different widely used RAID levels and when should I consider them? What is a Storage Area Network, and which benefits does it have over different storage solutions? Rack Mount Servers - Build them or Buy them? Hosting provider/server hardware shopping Dedicated server or Cloud Hosting? Use Google Apps/Cloud Services as a Domain Controller Replacement Infrastructure Software Can I have multiple DHCP servers on one network? Active Directory What is Active Directory Domain Services and how does it work? What is Group Policy and how does it work? Windows Active Directory naming best practices? What should the order of DNS servers be for an AD Domain Controller and Why? Difference between Microsoft ADCS Standalone CA and Enterprise CA DNS Should we host our own nameservers? How long does it take for DNS records to propagate? What is a glue record? How to use DNS/Hostnames or Other ways to resolve to a specific IP:Port Why does DNS work the way it does? Do internet standards require reverse DNS for every device? Is dig +trace always accurate? What is the role of NS records at the apex of a DNS domain? Why can't a CNAME record be used at the apex (aka root) of a domain? How do I understand my CPU usage on a DNS server? How can I manage all of my domains with minimal configuration? Why is geo-redundant DNS necessary for small sites? How do I set up a "secure" open resolver? Licensing Can you help me with my software licensing issue? Do I need a RHEL subscription to install packages? Networking Networking Units: Not getting expected performance from 100Mb Ethernet Loopback to forwarded Public IP address from local network - Hairpin NAT What tools can create a map of my network? What am I looking for in a Monitoring Solution? How does IPv4 Subnetting Work? How does IPv6 subnetting work and how does it differ from IPv4 subnetting? Switching to IPv6 implies dropping NAT. Is that a good thing? How do VLANs work? Exposing multiple servers behind NAT using a single public IP address Connecting to a remote server through a VPN when the local network subnet address conflicts with a remote network What causes the 'Connection Refused' message? How do I make protocol foo hostname-aware? General Unix/Linux OS Stuff Why is Linux reporting "free" memory strangely? Why is my crontab not working, and how can I troubleshoot it? Unix Server Partitioning & Filesystem Layout Install software from packages, or build it from source? Can you help me with my software dependency issue? Installing a third party application package on CentOS 6.4 fails due to missing dependencies libcrypto.so.10 and libssl.so.10 Why drop caches in Linux? Security Heartbleed: What is it and what are options to mitigate it? How do I deal with a compromised server? What permissions should my website files/folders have on a Linux webserver? What should I do about a "misbehaving" user? Restricted Shell: How to restrict the users' shell allowing to execute shell programs How to convince a big boss that he does not need administrator privileges? Tips for Securing a LAMP Server How do I deal with the removal/eradication of an unknown worm on our network? Why is "chmod -R 777 /" destructive? I am under DDoS. What can I do? SSH Does getting disconnected from an SSH session kill your programs? ProxyCommand: How to configure a shortcut for an SSH connection through a SSH tunnel Terminal Server (RDS) Find out the bottleneck for windows remote desktop server (Terminal server) Uptime 100% uptime for a web application reaching 99.9999% uptime Virtualization Enabling hardware virtualisation BIOS; anything to beware? Web Servers mod_rewrite: Everything you wanted to know about mod_rewrite rules but were afraid to ask Picking the right MPM (on *NIX systems): How do I select which Apache MPM to use? One-click (x)AMP: Why not use a WAMP stack? , Meta: What to do with XAMPP/MAMP/WAMP questions IIS7: What are the differences between Websites, Directories, Virual Directories, and Applications in IIS 7? SNI: Multiple SSL domains on the same IP address and same port? Host Header vs. DNS: How does pointing a CNAME on my domain to a service-provider's server enable them to offer customized services? Reverse proxy: How can I forward requests from my web server? Windows (General) Host files: Hosts file ignored, how to troubleshoot Law Can you help me with my GDPR issue? Meta Why SF is failing - the dismal future of ServerFault What information should I include or obfuscate in my posts? | {
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2,544 | The moderator election states that there are two positions open. With the recent loss of Chopper3, this means that this is a net gain of 1. There's some discussion with regard to the specific count for this election; maybe some more general discussion is needed on how many moderators are needed. Is there a Stack Exchange rule of thumb for how many moderators we need? Where did the 2 come from with this current election: Did someone decide this? Based on private discussion (by this I mean, "not on meta") with the existing moderators and their sense of the workload? Or does the system just have a random number generator for how many positions to open when an election comes up? I'm not going to include Kara in this list, as she seems to be inactive. I'm also not going to include Kyle and George, as my anecdotal impression is that they don't spend a lot of time on community moderation tasks these days (I don't see their names on a lot of closes, deletes, or migrations) -- correct me if I'm wrong on that. So, that leaves us with 5 moderators. From east to west: GMT +10: Mark GMT +1: splattne GMT +0: Sam GMT -5: sysadmin1138 GMT -8: mrdenny Most of us don't have any point of reference for the flag volume, and at which times it's heavy, but what I do know is that Chopper3 handled a lot of flags, and was getting burnt out from it. Picking up that load among the existing moderators plus two seems like people would still be forced to spend all of their time on the site clearing flags. This is something that's been discussed recently , but bears revisiting here; it (again, anecdotally) seems to me that two of our current community moderators are handling the bulk of the heavy lifting. Dealing with sheer flag volume is one aspect of this (which most of us can't speak to), the other is community faith in the moderators. Inactive or semi-inactive moderators may not be equipped to deal with flags appropriately; and even if they are , their lack of visibility to the community leaves a perception that they're disconnected from it. The Stack Overflow opinion is that moderators are moderators for life. Does that automatically apply here? Giving up the diamond has been a breath of fresh air for Phil; handing it off doesn't need to be a bad thing. So, to sum up: Where'd the 2 come from? If it's arbitrary, shouldn't it come from a discussion with the existing moderators, or else a public discussion on meta? Can one of our existing diamonds weigh in on what times of day need attention at this point? Do we need to adjust our perception of our current moderator count, if only a small subset of the moderators are handling a vast majority of the work? Do we need to add additional moderators beyond what we feel is needed, so that they all can spend a smaller proportion of their time on moderator tasks to avoid burn out? | Upvote if you think we should have three new moderators. | {
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2,717 | Currently, code highlighting is turned off (see balpha 's comment here ). It is possible to turn it on, if we want so. I think this would be nice to have, maybe on a per-tag basis, but turning it on is definitely the first step. Because it is disabled site-wide, we can't force it by manually specifying the language as described here . Caution : This vote is not about wether or not we should enable it automatically when a certain tag is used, it's wether or not we should enable code highlighting on the site. Upvote the according answer below. Update : I think it's pretty clear where this is going. Can anyone do this change? | Yes, I want code highlighting. This has been enabled, and at this time these tags inherited syntax highlighting and have it enabled. vb vbscript perl vb.net powershell bash sh shell-scripting The tags below have inherited code highlighting but it is off by default. oracle mysql delphi json haskell netbeans drupal-6 asp.net-mvc-2 boost drupal ios postgresql php qt .net-2.0 gcc .net-4.0 stored-procedures soap jsp asp.net-mvc servlets asp.net-ajax asp-classic c++ html5 lua ajax jquery codeigniter sql-server sql-server-2005 tsql sql-server-2008 c j2ee sqlite php5 ant wordpress cakephp flash xml zend-framework css ruby-on-rails c# hibernate django ruby javascript html coldfusion android regex vb6 wcf sharepoint http python sql database java asp.net .net plsql mono jboss Moderators can configure (include turning highlighting off) syntax highlighting for a tag on the tag info page. | {
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2,894 | After a successful edit round , it is time to vote on the results. The text below is the edited text we've worked on for the past week. This will be open until UTC 0:00 Friday (3 days!) to gather votes. As before, this will need a 2/3rds majority (only counting upvotes) for approval. If we don't reach it, we'll do a second edit round. Server Fault is for Information Technology Professionals needing expert answers on topics related to managing or maintaining computer systems in a professional capacity for their company or clients. If your question is about… Servers hardware Operating Systems, including linux windows-server-2008 freebsd solaris Server Software, such as apache2 exchange-2010 sharepoint Virtualization, including vmware-esxi hyper-v kvm-virtualization xen Enterprise storage Systems, including san fabrics and raid devices. Business Workstations Desktop PC Operating Systems, such as windows-7 windows-xp ubuntu lifecycle management, including configuration-management software-deployment and patch-management Network routing , switches , and firewall devices and administration Operations, Maintenance, and Monitoring: backup and disaster-recovery Service monitoring scripting and automation Supporting infrastructure, such as power , ups , cooling , and rack management and it is not about… Anything in a home setting . Product, service, or learning material recommendations. Career, salary, personnel, employment, or formal education. Licensing , law/legal advice, and circumventing security or policy. Unauthorized hacking, password cracking, or system abuse and misuse. … then you’re in the right place to ask your question! We also have sister sites that cover specific topics in more detail: StackOverflow for Programming. SuperUser for general Networking, Hardware, and Technology. Unix & Linux for general Unix/Linux usage. DBA for Advanced Database topics. IT Security for Advanced Security (implementation, theory, white hat). We also have… … a list of the most common questions with links to the "best" answer we've identified . | Yes, this FAQ is good enough. Approved. | {
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3,153 | I have viewed some profiles of SF users who have high reputations. One thing I have noticed that they have asked only a few questions. Some Profile links are given below: Evan Anderson Iain MadHatter womble SvenW Is it something like this that: As they are experienced, face few problems. They take services from other sources | You missed me off the list! 2155 answers, 28 questions :) Anyway the answer is that they, and I, are smart, experienced and resourceful. We've done this a long time, building instincts that help with fault-finding and know where to go to get answers quickly. We actually probably run into MORE problems than more junior guys, we're usually doing more so there's more to go wrong - but we can more quickly spot and solve problems than less experienced guys. Basically there's no substitute for experience. | {
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3,425 | Do any professional sysadmins really use cPanel, rather than provide cPanel? To me, cPanel is indicative of non-professional (i.e. voluntary, spare time, personal) web hosting use? Sure, I can see questions from people who run hosting farms and provide cPanel for their users having a place here, but every time I read a question with cPanel in the tags I think, this is surely someone who's not a professional sysadmin. Being the guy or gal your company made support your little website on a consumer grade hosting service that uses cPanel does not make you a sysadmin? https://serverfault.com/questions/402028/enable-my-users-to-create-their-own-eimails-using-cpanel https://serverfault.com/questions/400151/www-keeps-getting-added-to-subdomain Getting a have DNS error | A question that mentions cpanel is not de-facto off-topic. It is possible an otherwise competent admin inherited a cpanel disaster and now has to make it work. HOWEVER - If you are limiting yourself to just "what can be done from within cpanel" you're no longer a sysadmin in my view - you're an application user, and all of your questions should be referred to the application vendor (cpanel). The distinguishing factor in my view is that a professional sysadmin may (grudgingly) use cpanel as a tool, but they are willing and able to step outside the tool to get things done. and they typically provide enough other information about their problem to be helped along. As Ladadadada pointed out these questions are generally crap for other reasons, like lack of information. Crap questions are crap questions, and should be dealt with accordingly regardless of their content, though being "about cpanel" is generally a good marker for "this question is probably crap"... | {
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3,458 | I just downvoted an answer for the first time today, and noticed that I lost 1 reputation score. Obviously 1 "point" isn't a big deal. Whoop-dee-doo! But on a serious note, what's the reasoning behind this? My guess:
Discourage users from unnecessarily downvoting on things, so that only, truly, those questions/answers are "bad" are downvoted upon? | Discourages users from unnecessarily downvoting on things, so that only, truly, those questions/answers are "bad" are downvoted upon. | {
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3,724 | A new user just registered and posted two spam posts, one of which was very long. Both posts started to get downvoted very quickly, and a number of close votes were made. The questions were live for around 5-10 mins, before they got deleted: https://serverfault.com/questions/436391/telemarketing-services-in-pakistan https://serverfault.com/questions/436393/b2b-marketing-services I made an edit to both posts to remove the bulk of the text, to reduce the chances of anyone clicking on the links to the website in the 'questions' that had been posted. Editing the post in this way didn't seem the right thing to do, should have I left the question alone and just waited until a moderator deleted it? Thoughts please? | The best thing to do is flag and downvote. Flags don't generally get left hanging around for long and enough of either will cause the post to be hidden/deleted automagically. 6 Spam flags will cause automagic deletion. | {
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3,982 | As it is December 2012, we are now going to reset our Community Promotion Ads for the new year. What are Community Promotion Ads? Community Promotion Ads are community-vetted advertisements that will show up on the main site, in the right sidebar. The purpose of this question is the vetting process. Images of the advertisements are provided, and community voting will enable the advertisements to be shown. Why do we have Community Promotion Ads? This is a method for the community to control what gets promoted to visitors on the site. For example, you might promote the following things: cool server utilities the site's twitter account script packs or power tools cool events or conferences anything else your community would genuinely be interested in The goal is for future visitors to find out about the stuff your community deems important . This also serves as a way to promote information and resources that are relevant to your own community's interests , both for those already in the community and those yet to join. Why do we reset the ads every year? Some services will maintain usefulness over the years, while other things will wane to allow for new faces to show up. Resetting the ads every year helps accommodate this, and allows old ads that have served their purpose to be cycled out for fresher ads for newer things. This helps keep the material in the ads relevant to not just the subject matter of the community, but to the current status of the community. We reset the ads once a year, every December. The community promotion ads have no restrictions against reposting an ad from a previous cycle. If a particular service or ad is very valuable to the community and will continue to be so, it is a good idea to repost it. It may be helpful to give it a new face in the process, so as to prevent the imagery of the ad from getting stale after a year of exposure. How does it work? The answers you post to this question must conform to the following rules, or they will be ignored. All answers should be in the exact form of: [![Tagline to show on mouseover][1]][2]
[1]: http://image-url
[2]: http://clickthrough-url Please do not add anything else to the body of the post . If you want to discuss something, do it in the comments. The question must always be tagged with the magic community-ads tag. In addition to enabling the functionality of the advertisements, this tag also pre-fills the answer form with the above required form. Image requirements The image that you create must be 220 x 250 pixels Must be hosted through our standard image uploader (imgur) Must be GIF or PNG No animated GIFs Absolute limit on file size of 150 KB Score Threshold There is a minimum score threshold an answer must meet (currently 6 ) before it will be shown on the main site. You can check out the ads that have met the threshold with basic click stats here . | {
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3,999 | I asked this question, which got a great answer, but was voted to close. My question is, why? From what I can see, it appears to be well within the scope of the site (networking). Are the use of WiFi extenders considered to be non-professional grade? | {
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4,111 | This is part of a set of questions on how Server Fault defines "professional" system and network administration. For additional information, see: Why "professional capacity"? The About page says at the very top: ... related to managing computer systems in a professional capacity . What does that 'professional capacity' mean? I get paid to do what I do, so isn't everything I do relating to that capacity topical? | Not really. First of all "professional" is more than just a job-description with a paycheck, it's a mindset. But more on that later. Over the years the ServerFault community has evolved a rough consensus definition of what that phrase means. There are two broad categories we assess new questions against regarding 'professional capacity'. The system being asked about is a production system. Knowledge, asking style, and evidence indicate that the asker has the right mindset (a.k.a. the "is a professional" test) The first is more concrete and overlaps with a few other items in the FAQ under NOT About . The second is much more complex. Production Systems This is more of an exclusionary line. Questions that fail this test are also likely one or more of: In the home (failing the anything in a home setting and likely career education points in the FAQ) Being built purely to learn new things (failing the career education point in the FAQ) Hypothetical what-if questions (failing the career education point in the FAQ, and a big risk of failing the is a professional test, see below) Development systems (likely failing the anything in a home setting point in the FAQ, and debatably more topical on StackOverflow) We've found that scoping "professional capacity" to just production systems does a great job of keeping questions definitely topical. Of these the development systems item gets us the most pushback. There are very good reasons we eliminate these systems from consideration: The SO FAQ states that "software tools commonly used by programmers" is topical. The large majority of such questions ServerFault gets relate to setting up development environments on laptops or virtual-machines on laptops. Apple laptops and Virtual Box VMs are two areas that professional sysadmins have very little professional experience with. Such installs typically use frameworks not actually used in production, such as XAMP/LAMP/MAMP installers, which sysadmins have little experience with. Such installs commonly use configuration settings that are against best-practice for production systems, which sysadmins have little experience with. However, some questions related to systems which are not nominally production may be on topic, particularly if they meet certain criteria: The question does not relate to a constraint or condition that would never exist in a professionally managed production environment (such as problems which arise from using virtualbox on a laptop). The non-production (eg. UAT) system accurately reflects the production system in all material respects. The problem relates to a change that will be migrated into a production environment once the problem is solved. A question about a non-production system which does not meet at least those three constraints will certainly be off topic. Is a professional Good questions are ones that demonstrate that the asker has the mindset of a professional sysadmin. A question that passes this test demonstrates several of the following qualities: Shows that they've done some research before coming here, usually by including the results of their failed searches. Uses professional language instead of casual, vulgar or shorthand. Knows enough about their problem to include the right details instead of all of the details. Shows sufficient skill in the technology under question to be able to work on it for pay. Demonstrates knowledge of better-practices through how their environment is put together. Most hypothetical what-if questions frequently fail this test, though some don't. | {
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4,140 | Well, it's January, which is the traditional time to hold a moderator election on Server Fault. My question is; do you think we need one? I'd like input from everyone - new users, regular users, high rep users, current moderators and even SE staff. Things to note: We haven't had any moderators retire in the past 12 months If you think we do need an election, state how many people you think we need Do we need to focus only on a specific timezone/timeframe? This is not an official moderator election thread; if people decide we need one then we still need to approach SE themselves and ask them if they concur, as they have the final say. | As I write this, there seems to be a general movement towards "don't need one", with which I agree. But if we decide not to, I think we should reserve the right to have one later in 2013 if it proves needed. That is, instead of saying " we don't need one now, the next one will be January 2014 ", we say " we don't need one now, so we won't have one now; but we'll have one later if it's needed, and either we'll have an election or we'll have this discussion again no later than January 2014 ". Perhaps this is an unnecessary caveat, and it's just the sysadmin in me wanting to set expectations correctly - but you're all sysadmins too, so you might identify with that! | {
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5,337 | The comment thread and reaction to the original poster of this question was completely out-of-line. https://serverfault.com/questions/494996/what-are-the-bare-essentials-to-make-ubuntu-production-ready-for-a-public-websit This went from something that could have been informative to a absurd attack on developers... I'm not sure why people piled on the original poster. Some of the responses were disrespectful. Start-ups with dev-only teams are not an uncommon scenario these days, and there are plenty of situations where access to a qualified systems engineer isn't easy. I understand that there's friction between the traditional systems administration community and the increased presence of DevOps and developer-driven architectures, but it's here to stay!! There will be more Ubuntu questions, more basic infrastructure inquiries from people who have had little experience with enterprise hardware and definitely more people who haven't "paid their dues" in the same way old-school sysadmins have... New paradigm. But it's not an excuse to berate someone coming to Server Fault for help. "Hire a sysadmin" isn't constructive on its own... | As a long time lurker ServerFault is infamously known for its hostility. Several times I have considered reporting certain users due to their consistent history of attacking the OP and arrogance with their knowledge. That doesn't make a healthy Q&A site. I also disagree with the idea that eliminating the "professional capacity" requirement will drive experts away. Take a look at StackOverflow's top monthly users , most have large amounts of reputation and experience. Even with the massive amount of low quality questions they are still doing fine. In this case the main problem is not the question itself, its the broadness of the question. To me its perfectly reasonable to close the question as NARQ since building a public server means talking about OS level security, firewall security, application security, secure coding practices, etc. That's a lot for a single question What I do NOT agree with are the multiple users who flat out attack the OP. Yes, in an ideal situation you would hire a sysadmin (or at least outsource it). However, in an ideal situation you would also hire a lawyer for every single non-critical law question you have instead of googling, hire a general contractor to install a dishwasher or stove, you would never fix your car yourself and instead go to a certified mechanic, and you would never attempt repairs computer or phone problems by yourself. However, I bet most people do things like this on their own even though there's risk of damaging something but ended up doing just fine in 90% of cases The proper response would be similar to law questions: "IANAL, but..." The proper and best thing to do is hire a sysadmin or at least outsource it. They will know how to secure the system better and manage it in a production environment. If this is absolutely not an option, the following resources will be helpful in getting you started. Note that you have real risk of suffering downtime, security vulnerabilities, and system instability, but these resources will attempt to limit those. Try to make it a goal though to have a sysadmin as soon as you can link to the several hardening Linux/LAMP questions link to a description of different services link to why desktop GUI is bad on a server (multiple questions on this, could also use Windows Server Core as an example) Now was that so hard? You've made very clear this is the wrong way to do things and may cause bad things, but have provided a long list of resources to help get the OP started. This both discourages the behavior but answers the question in a nice easy way. You get the best of both worlds | {
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5,414 | There are cases where old, barely supported or possibly unsupported server-class systems (be it software or hardware) are still being used professionally; for instance: Low-budget operations (still commercial, just not big); The system can still perform well for its intended purpose, and downtime is not catastrophic given the use so vendor support is not as critical; Existing in-house-developed systems that would not be cost-effective to change make use of it. What would be good guideline(s) on the threshold where such a system can still be considered on-topic here? | As far as I can see, all of those cases are on-topic at ServerFault. The main requirements are that the questions should be about a professional setting, and from the perspective of the person in charge of keeping the systems running. However, given that many of us have used bleach to scour clean the parts of our brains where we used to store information about e.g. Windows 3.11, we may not be able to help. In other words - ask away, but the responses won't necessary be what the asker wants to hear. So that's pretty much business as usual. | {
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5,449 | There is a currently private beta site for Network Engineering here: http://area51.stackexchange.com/proposals/52519/network-engineering The beta is new, but seems to be garnering a decent following so far, and will probably ramp up participation when it becomes a public beta site. I think this new site should exist...as this is a core role/area within IT. But only if these topics aren't to be covered by ServerFault. After all, why have a separate site at all if the topics can and should be covered here? Given that the ServerFault FAQs state that a question can be about: Network routing, switches, and firewalls and the site name is Server fault...is the idea to get back to a core based on the name of the site, centering around questions regarding server/application administration and moving networking questions to their own site, eliminating this from the FAQs and acceptable topics? Or do sites like this new Network Engineering one exist as supplements to the larger sites like SF and SO for more granular or specialized help? If so, what happens when these questions overlap (ie. serverA cannot communicate with serverB)? | Don't get hung up on the name. Seriously, servers are a small fraction of our topicality. I've heard this argument many times now and it's getting really old. If we made subjects off-topic here when another site covered them, there'd be nothing left. | {
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5,463 | This came up in relation to the upcoming mod election, e.g. Dennis' question here, and tombull89's and Iain's comments here, but I think the discussion of this shouldn't be limited to "what do the the candidates think they would do to change/improve SF?" I don't know if everyone would completely agree with Iain's comment, but I suspect most of the regulars would agree there is a problem, and this is not a bad way of summarizing it: SF is no longer by professionals for professionals it is by
professionals for amateurs and if you try to fix it then you're
considered hostile and unfriendly So the purpose of this question is to focus on whether there's anything anyone (mods, users, SE staff (?)) can do to improve the disconnect between the professional sysadmins that the site is supposed to be aimed at and other people who use the site. | My general thoughts -- First we need to (re)define what our scope and target audience is. Our FAQ currently says "Information Technology Professionals" -- this was arrived at after much debating during the great FAQ rewrite ( sffaq ) because we did not want to exclude members of our target audience of system, network, DB, etc. admins. The more I think about this the more I think we were too broad: developers are "Information Technology Professionals", and many of the clueless masses doubtless consider themselves so. Perhaps we should consider narrowing the scope of that line to more clearly define who we are looking to serve. Along the same lines, we have had many discussions on Meta about the requirements of a "professional", but those are not articulated anywhere in the FAQ. I believe we should spend some time crafting a FAQ section that specifically addresses what professional means in the context of Server Fault. Then we need to enforce it. This means closing questions that are clearly not a fit for the site -- most of which fall into a few categories: Too basic The asker lacks the requisite technical background to understand what they're asking. Questions like "How do I get a list of IP addresses on an interface?" fall in this category. Often the user isn't even the system/network admin of the environment in question, in which case these questions really belong on one of Unix & Linux , Super User , Ask Different , or Ask Ubuntu . No Research These are the "How do I make Apache log the remote IP?" or "Give me a tutorial on X " questions -- the answer is plainly available in documentation (or a Google search), and the asker is being lazy. No Troubleshooting "Apache is giving me a 404 error - HELP!" type questions. These are often asked by 1-2 year junior admins (or people thrown into an admin role without experience) who are apparently mortally terrified of asking their superiors questions or admitting they don't know something. As a result they ask lousy, unanswerable questions. We have a meta topic to guide them toward writing a good question, and this sort of rot should be closed with a link pointing there (and reopened if fixed). The Summer of Love and The Winter of Our Discontent I don't like that Server Fault has a reputation of being "the mean Stack Exchange site". I also don't think it's spilling any great secrets that Stack Exchange doesn't really want one of their sites viewed as mean either (after all they thrive on traffic, and mean sites don't get much traffic). The growing hostility toward new users (mainly on Stack Overflow and Server Fault) was the impetus behind last year's Summer of Love . That said, in order to keep Server Fault from becoming "Technical Support For The Intertubes" there is an extent to which we must disappoint the clueless masses who think that's why we're here. System Administration has a time-honored tradition of "Read The Fscking Manual" for a reason -- those who can read and interpret documentation and apply what they've learned to new situations will likely become good sysadmins, and those who can't (or won't out of laziness) are frankly not suited to be professional system administrators. Enforcing this 40-plus-year-old cultural standard with neophytes is how the profession self regulates. There's nothing wrong with doing so here, as long as we don't devolve into berating people in comments. Remember that we are a site for professionals , which means that the main site should always maintain a level of professional decorum and courtesy, even when we're telling someone they're in the wrong place or their groundwork doesn't meet our standards. | {
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5,586 | I'm seeing more questions to do with RaspberryPi boards. This latest one set me off: Why can't I stream more than 1 file using nginx? Is there a belief that RaspberryPis can be used in a professional capacity that would justify their inclusion on ServerFault? How should we handle questions that include Raspberry-Pis as a foundational element in the scenario? My Opinion I'll put my opinion here rather than adding an answer of my own below. I believe that the limited nature of RaspberryPis, the hobbyist culture, and the self evident lack of enterprise anything with the board makes it totally outside of ServerFault's scope. Any service that is built using RaspberryPis and is having problems is tainted by the experimental and developmental nature of the Raspberry-Pi. I think questions that include Raspberry-Pis as a main player in the scenario should either be edited to remove the reference (bad) or simply closed as Off Topic (good, since editing out the Raspberry-Pi reference will obfuscate the potential root cause). | NO To expand: We're already leery of questions about home routers... they could conceivably be on-topic if it's a sysadmin trying to make remote access work, but few (if any) of the home router questions we get make the cut. Many of us (e.g. a certain cat-head-avatar person) are dubious about things like DD-WRT: repurposed home hardware used professionally. I think DD-WRT and its ilk are also borderline: they can be used professionally (I use it at work), but the hobbyist nature shows up in lack of support, iffy documentation, and so on. So by the time you're talking about general-purpose, hobbyist systems like the Pi, I think you're way over the line into tinkering for fun, not professional. Again, the lack of support, documentation, examples of realistic professional "server" use are the distinguishing features. | {
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5,592 | If someone can explain to me why the following was closed as 'off-topic', I would appreciate it. I will use the feedback to improve the question or just remove it. Thank you | NO To expand: We're already leery of questions about home routers... they could conceivably be on-topic if it's a sysadmin trying to make remote access work, but few (if any) of the home router questions we get make the cut. Many of us (e.g. a certain cat-head-avatar person) are dubious about things like DD-WRT: repurposed home hardware used professionally. I think DD-WRT and its ilk are also borderline: they can be used professionally (I use it at work), but the hobbyist nature shows up in lack of support, iffy documentation, and so on. So by the time you're talking about general-purpose, hobbyist systems like the Pi, I think you're way over the line into tinkering for fun, not professional. Again, the lack of support, documentation, examples of realistic professional "server" use are the distinguishing features. | {
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5,874 | Came across a site today which appears to be blatantly scraping SF content - and even has a similar name. The SF result was actually ranked below that of the external site. A search of mSO and mSF didn't turn it up, so I figured it should be brought to the community's attention: Site: FaultServer.com (the browseable list of questions on their main page is limited, but if you go under a tag, you get a fairly comprehensive list. e.g.: http://www.faultserver.com/l/linux_question/1.html ). Sample post: Serverfault: http://serverfault.com/questions/529394/nginx-connect-failed-111-connection-refused-while-connecting-to-upstream FaultServer: http://www.faultserver.com/q/answers-nginx-connect-failed-111-connection-refused-while-connecting-to-upstream-529394.html Screenshot of Google Search: | @MichaelHampton's post was rendered obsolete today. The new method of reporting purloined content is: Send all reports of SCRAPERs to [email protected] . Please include: the URL of the copied post the URL of the original post on SE for high-rankers, the search string you used (and the name of the search engine, if not Google) any other details you noticed and want to share, because you're awesome The full (contrived) Q and official A are here: A site (or scraper) is copying content from Stack Exchange. What do I do? | {
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5,931 | tl;dr: in the tooltip for upvoting/downvoting of questions is the semicolon(;) considered an and/or (meaning do we upvote if it is clear and useful but no research, or upvote for research but not clear or useful)...or is it "upvote because the question has research effort, and therefore is clear and useful"...or other? Looking at a few of the questions today (not to pick on anyone, just as examples): This question: Managing Windows 8 Start Screen Tiles (at the time of this post) has 4 upvotes and yet per Jeff Atwood here: In what cases am I meant to downvote a question? the tooltip should be the basis of voting up/down. In this case the question clearly has no research effort but has been upvoted as if it did. A more recent meta question regarding voting on questions is here: What are the reasons a question can/should get an upvote or downvote on Serverfault? where Iain reiterates Jeff's point on why/when to up/downvote a question. MDMarra also points out in that discussion: ...we fully expect you to have put some effort into solving your
problem before you come here. We also expect you to have done some
research before you come here.... So, not to pick on Mark, but his question recently: Is there reserved OID space for internal enterprise CAs? also shows a lack of research. Now, I know he wouldn't post a question without researching it, and I know his background and expertise, and the high rep count always lends to favorable treatment, but should the question be upvoted based on the tooltip? I like the question and upvoted it myself, so I'm just as guilty as the next guy (unless it is perfectly acceptable to upvote based on "usefulness to the community" and disregard research included). The same could be said for this HIGHLY upvoted question: What are the advantages of tape drives? In contrast this question appears to have research: What is /etc/apache2/sites-available used for and is it necessary? as does this one: Hyper-V File Server Clustering - at my wit’s end and both had multiple downvotes. It would appear that while sometimes we vote on questions based on research, a lot of times we vote based on whether we like the merit/premise of the question regardless of the research done. So, is that perfectly valid? | Man, no wonder you guys don't vote enough, you're seriously overthinking things... vote up questions you think are good vote down questions you don't think are good The tooltips are just that: tips. They're not definitive, legalistic definitions of when you must up or downvote, they're just short summaries of the most likely reasons you'd consider a question to be good or bad. Looking at the other answers, my thought process for voting up is similar to voretaq7's: if it's clear what they're asking and I think it's useful to myself or another professional, that's good enough. For downvotes: When reviewing, I routinely click on the questions I think are bad and downvote them (if they're not already) so that if they do get closed the auto-delete process will nuke them. But since unanswered closed questions only need -1 for the auto-delete to get them, there's no need to vote them into oblivion. Redundancy between votes and closing is a feature : you want to close the really bad questions, but in the meantime you want them appropriately downvoted to show that they're bad. | {
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5,936 | https://serverfault.com/questions/554486/backup-restore-oracle-virtualbox-vm?noredirect=1#comment641555_554486 It seems silly to post about it here but the moderator insisted that I do so, which he enforced by closing the comments section of the thread. This is despite the fact that on-hold questions specifically tell you to "leave a comment". Anyway, see my discussion in the comments reproduced below-- It seems obvious that as per the site rules, the question should be open. It's an enterprise virtualization product according to Oracle. I'm asking a question about backups. Both things are explicitly stated as OK according to the rules. It's doubtful I'll be posting any more questions on this site. Why take the time to formulate a question if it's not clear whether it will be left open? | Man, no wonder you guys don't vote enough, you're seriously overthinking things... vote up questions you think are good vote down questions you don't think are good The tooltips are just that: tips. They're not definitive, legalistic definitions of when you must up or downvote, they're just short summaries of the most likely reasons you'd consider a question to be good or bad. Looking at the other answers, my thought process for voting up is similar to voretaq7's: if it's clear what they're asking and I think it's useful to myself or another professional, that's good enough. For downvotes: When reviewing, I routinely click on the questions I think are bad and downvote them (if they're not already) so that if they do get closed the auto-delete process will nuke them. But since unanswered closed questions only need -1 for the auto-delete to get them, there's no need to vote them into oblivion. Redundancy between votes and closing is a feature : you want to close the really bad questions, but in the meantime you want them appropriately downvoted to show that they're bad. | {
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6,099 | Today we had someone ask a question regarding a discussion they had had with their manager. For all we know they may want to show their manager the answers they got here. Unfortunately the text below appears in a comment. Your boss doesn't know his ass from an SMTP relay. So, uh, good luck with that. May as well let him implement his stupid plan, though, get some experience with Cisco ASAs and use that experience to find a boss who's less stupid I don't think that the above needs to be said on SF where, after all we're all meant to be professionals. Name calling like this is rude, isn't the act of a professional and makes me sad. That I flagged the comment and my flag was declined makes me sadder. Should we really be promoting this kind of language on Server Fault? | Absolutely not! It would have had greater effect if it read: Your boss hasn't given you any substantive reason, in saying this. You should definitely ask for more details (we can't possibly give an answer with just this), and if it is a consistent and serious problem it might be better for you professionally to seek employment elsewhere. You could also just let it go. The cumulative effect of the comment as quoted by Iain is such that it has no redeeming merit and the flag should have been accepted; it is not a constructive or professional comment even in our profession. | {
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6,124 | I answered a question today while knowing little about the subject, and all I did was Google. True, some googlers are better than others, and perhaps I deserved the 1 upvote I got for such. However, if the OP needed more in depth detail in regards to his question, perhaps commented to my answer, I wouldn't have that practical experience to elaborate. So, should someone post an answer without having sufficient practical knowledge on the subject? | The aim of the site is to be a replacement for search engines, so good answers are where you find them: there's nothing wrong with an answer that's based on a bit of googling, as long as it does answer the question and it isn't a straight steal of someone else's work (we've seen answers that appear to be someone just cutting and pasting vague results of a search, which isn't so good obviously). I think this happens more than it might appear. Sometimes I see something here I feel I "ought" to know or want to find out about because it's close to one of my areas of expertise. If I then dig into it to find the answer for my own curiosity then at that point, putting up an answer is just sharing the results of research. That's a good thing. If someone needs something more in-depth then that's leaving room for another answer that will hopefully get votes too. | {
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6,195 | ...or sometimes both ! ESXi 5.1 crashing (bug fixed by updates) Installing XenServer 6.2 on Proliant DL160G6 freezes during "Installing from base pack" (firmware) Disconnected Network Adapter on VMware - only power cycle solve this (firmware) Unable to view sensor data in ESXi 5.x on DL380 G7 (bug fixed by updates) Why is VMware ESXi 5.5 crashing? (bug fixed by updates) ESXi host losing connection to vCenter (bug fixed by updates) HP ProLiant with SATA/SAS Drives (firmware) Is this a basic troubleshooting step that people are missing? Maybe it's that VMware and HP solutions require more massaging and care than others, but my impression is that people simple aren't making the effort to keep their environments updated and run into bugs as a result. In a time where software updates are mandatory for general purpose operating systems, our phones, televisions, bathroom scales and even my bicycle , why is it missed so often in the server hardware and virtualization space? Is there a cleaner way to answer these questions or suggest, "are you on a recent revision of software|firmware|BIOS?" at the time of posting? | It's very useful to know that a particular version of software/drivers/firmware actually fixes the problem that someone is describing, so these answers can be incredibly helpful to other people facing the same problem (especially people for whom upgrading firmware may be a practical problem, e.g. in production systems, high availability systems, or just people who really want to understand the root cause of their problem instead of randomly gefingerpoking until it goes away) | {
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6,229 | What can you do to prevent going down the rabbit-hole of answering a question where the original poster just doesn't get it ? Questions that seem innocuous or should have a straightforward answer quickly devolve into comments that reveal how big of a mess the OP is really in. And maybe I'm looking for a more graceful way to exit. Start with this - a disk failure: HP Proliant DL180 G6 - Smart Array P410, bay 11 error From there, it goes into conflated error messages, YouTube videos , screenshots , firmware, lack of documentation, an explanation of RAID and ends with multiple suggestions to just replace the disk ... But wait, how DO I replace the disk? And why is my system with a failed disk performing slowly? And even more tangentially-related fallout . Oh, and finally , "How do I check the progress of the disk rebuild?" Is this the state of Professional in 2014? Or this simple FreeNAS drive failure: zpool status reports error ... what next? "Replace the disk" This spawned numerous followup questions ( some with great . answers . ): Need to identify disk in zpool ... how? Need to replace disk in zpool ... confused FreeNAS: "/var: write failed, filesystem is full" FreeNAS: "swap_pager: I/O error - pagein failed" But in the end, looking at this in the context of the poster's history, there was nothing but a disastrous string of bad situations , each linked to the previous. Is there a point where you just give up? If I were an employer or this poster's superior, I would have serious concerns about their ability to solve problems or that they were wasting time with a solution they could not manage effectively. Yes, this guy, too! HP ProLiant DL380e Gen8 has high fan speed after installing second CPU A server with a fan speed issue following a hardware modification. Poor feedback to requests for more information. Normal OS and firmware recommendations made sense, given the environment described. OP had problems updating firmware ... Poor followup. After 2+ weeks: After upgrading all the software, the fans kept blowing 99%. However I suddenly noted a warning during boot time that fan 1 was missing - I switched fan 6 to slot 1 and the issue is now resolved. What about the front-panel indicators on the server that clearly display fan status and hardware health?!? The ILO? The POST messages during the OS and firmware updates? And what if the fan is still bad? Motherboard issue? Facepalm :( Or a networking question: How to use iSCSI MPIO to increase bandwidth with XenServer? I saw back-and-forth in the comments section. Multiple users tried to explain the flawed logic of the question via comments. One excellent answer was posted, but the OP still wasn't on the same page. I gave a terse explanation describing what the real focus of the issue should have been. Maybe it was colder than intended, but I notice that a lot more hand-holding is needed in questions that should not require it. (Sometimes guidance is necessary, but there's a difference between working with someone knowledgable who's in a bind and teaching someone the basics along the way to answering a question) | Others have said you should “Just walk away.” and “Stop doing it.” but I wanted to add a small piece of advice. Looking at your reputation of 89.5k in addition to they type of question you are asking, it’s clear to me you have deep skills based on years of experience and (key point) you most likely gained those skills during the computing era when there were less techs doing similar work. I can relate. I have 20+ years experience doing Unix/Linux work to varying degrees. And in the early days the level of entry to learning this stuff was higher. So your skills had to be better and—key point here—people who had that pre-existing experience were more of mentors to new folk learning these skills. Why? Easy. As proud as we are for our skills, nobody can do this alone. And honestly I hate being in a position of being the only guy on staff who knows something. Spread the wealth! Which is all to say that nowadays, the level of entry is much lower & many problems don’t need deep skills to solve most of the time. Just throw someone who kinda knows how computers work, throw them some money & BOOM you have an I.T. department. But the second the proverbial crap hits the fan, these guys are up a creek without a paddle. It’s not your problem. And life goes on. They are in over their heads and—are most likely—getting paid to be that incompetent. What do you gain by doing free work to help someone who is clueless? I sometimes get caught in a mess when I answer a question as best as possible & then it is clear that the original poster has no clue & basically wants you to do their work for them. I react to this in different ways, but honestly you cannot expect to post ad infinitum to a brick wall that has no clue. You answer the best you can, and move on. And here on the Stack Exchange of sites, just flag a question as a problem if you feel the original poster is wasting everyone’s time. | {
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6,291 | There are questions that get asked, from time to time, whose answers are fundamental and blindingly obvious to anyone with a reasonable amount of knowledge about the topic being considered, such as this one: Using DHCP, is it possible to obtain an IP address & MAC address for a cluster? These questions are easy to answer, and assuming the asker is willing to learn, provide substantial value to the person asking as well as to anyone trying to learn how things all get put together later. The answers will explain a fundamental concept. On the other hand, they might also conflict with the broken windows theory, and could often be answered in a moment's researching the topic. Is it really appropriate to close these questions? Or, is it sufficient to simply downvote them but allow them an answer? Or should we not even downvote them? | Everyone has a different definition of what is "blindingly obvious". We all have huge gaps in our knowledge. The smarter you get, the more you realize how much you don't know. There are plenty of questions I've asked that were obvious to someone more experienced with
the particular software/hardware/whatever than I was. And there are plenty of questions I've answered where I've had to take a step back and say " Ok...if you're asking me if I can do X with Y...you clearly have no idea what Y is for...lets explain that first. " That's the whole point of this site. I'm an expert in some areas. You're an expert in other areas. And if we all get together and share that knowledge, we become experts in a lot of areas. That said, there are a lot of questions (and I'm far too lazy to dig up examples at the moment) of questions where I could safely say " If you don't know that already, and couldn't find the answer for yourself, you don't know enough to be charging someone money for your work. " With many of these questions, they show absolutely no effort to find the solution on their own, and I vote to close them as "demonstrate a minimal understanding..." My cutoff point for those questions is typically something along the lines of "could I type that question into google and get the answer in under 5 minutes". The example question is on the better side of bad questions, but I would have voted to close it, and recommended the asker read up on how IP and MAC addresses work. | {
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6,462 | I just read this question , which seems like a reasonable question. The first answer posted also seems like good response, which I was about to vote up on, when I noticed that it was both posted at exactly the same time as the question and had the same author as the question as well. The policy is that answering your own questions is encouraged , which is all well and good, but feels to me that in this case it defeats the purpose of the Question & Answers format. It is not so much that after asking the author did further research and/or that the comments and other incomplete answers lead to a genuine solution which the author was good enough to share. In this case there appears no genuine question in the first place; the only reason the question seems to have been asked is to allow the author to post his answer. I have commented, down voted and voted to close on other occasions with the remark if you want to document your own learning experiences you should write an article on your own blog instead. But what is the policy or conventional wisdom in these cases? | To add to MichaelHampton's answer, the SE network encourages this style of information sharing, which is why it was made possible a while back to ask a question and post an answer at the same time. (this wasn't always available) Update Also see this SE blog post on why this ability was added. In short, they want to take the good parts of blogging, which you kind of despised judging by your question. Some of us have been doing this lately to stay active on main, and also to 'centralize' more and more scattered technical information on the internet into a single place, which can be authoritative. For example, there have been times I've had to scour social technet and found here-says and maybes, and the OP never confirms if proposed solution works or not. If I try it and find it working, posting on SF with a relevant title has the benefits of helping someone else who googles the problem (since SF posts have a super high google ranking), and I potentially gain reputation, and SF potentially recruits a new member. Also, what happens when you pose a question on SF, no one answers, and you finally figure it out after weeks/months/years of troubleshooting? Go ahead and answer your own question. It floats back to the front page, and you may even earn magical internet points for your efforts. People may not have known the answer, but they do know good troubleshooting when they see it. Several of my self answered questions: VM freezing during WinPE boot up SCCM Task Sequence Error 0x8007000E Ensure drive is mapped at login on laptop with strictly wireless | {
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6,523 | While Googling for a utility a few weeks ago, I came up against this question: Automated method to convert .reg registry file to reg.exe commands Which was exactly what I was after. However, the only answer had been flagged as spam. Due to my rep points, I was able to see that the answer pointed to here: http://www.sordum.org/ While the link was broken, they do make a product ( http://www.sordum.org/8478/reg-converter-v1-0/ ) which is exactly what was requested. I flagged this answer as not spam, but it was declined. Why? | Having just spent several minutes weed-whacking a bunch of similar posts from hopeful marketers trying to provide tool suggestions to people having problems, I can say that such tool-only posts are an invitation sign to a lot more. Every morning I have to deal with one to three such posts. Since you have the rep to see it, take a look at the deleted history of this question: How can I extract email (in a PST) from an Exchange 2007 EDB file? There are 5 deleted answers all from tool-vendors hoping to be the one that provides the (paid) lifeline out of a problem to someone, or someone with a similar problem looking for answers. ServerFault used to allow such posts, it couldn't be link-only but had to be directed at the question itself and not copy-pasted to a bunch of questions. Two-ish years ago there was a community change as a whole to start spam-flagging them. There were a few solid months of people dutifully mining old questions for just that kind of answer to flag and made a lot of work for us moderators. The big problem with this kind of post is that it is a signal to other marketers that such backdoor marketing is welcome and we had many questions end up with six answers all from tool vendors saying 'my tool works too, just FYI'. We had several debates in mod-notify with some of these marketers that cites, "Well, it's allowed HERE <link> so why am I getting the mod-hammer?" which made us have to weed-whack THAT question too. It leads to a sense of entitlement on the part of the marketers since there is no clean way to discriminate between actually-helpful and spam, so the decision was made as a whole to flag it all as spam since spam-bait is just as bad as the spam itself. | {
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6,701 | In the nearly 4 years that I’ve participated on Server Fault, it’s been a community that I’ve been proud to be a part of, and I’ve been able to build my own skill set a lot and help people out at the same time by answering questions. Everyone who’s helped to build this community should be proud of what it’s been able to do. We really have one of the best places on the internet to find answers to real problems that sysadmins face every day, instead of just inscrutable documentation or forum threads filled with crappy cargo cult solutions. For most of us, the profession of system administration is fundamentally changing: instead of duct-taped together automation scripts, we have a huge ecosystem of configuration management tools; instead of applications running on one server in one data center, we have applications running in distributed data centers or hosted in the “cloud”; instead of just needing to be an expert in an operating system, we need to be able to solve problems with a myriad of OSes, applications, databases, and protocols. All of these new problems need new solutions, and require sysadmins to reach outside of our comfort zones in lots of new ways. Instead of being able to kick the network issues to the network person, our systems need to be aware of the network, have the network configured in the right way, and even manage the network as software defined networking starts to catch on. Instead of getting an application out of the box that just needs a next-next-done install, we need to be able to understand how best to architect a solution for our specific environment using several different software solutions, and how to integrate those pieces of software. We need to be able to learn and evolve extremely quickly to keep pace with technology and the state of the craft. Staying up to speed is incredibly difficult in this profession, and getting in the door is getting harder all the time. For me, Server Fault is a great resource for maintaining my own knowledge and improving it - accidentally referring back to a problem I solved years ago because it comes up in a Google search, or having coworkers ask me to help clarify an answer of mine they found while trying to figure out a problem (this happened at my last job), tells me that we’re really helping to advance the field of system administration as a whole. But, I’m worried that we’ve gotten off track lately. There’s been a drop in participation through contributions - post rate, answers per question, and relatively active users (5+ posts per week) have all been trending downward for a while. Since June of this year we’ve seen a major jump in traffic - nearly 100% - due to changes to Google’s page ranking, with an accompanying jump in participation through community moderation (mainly close votes and down votes): ...but, crucially, not an increased volume of questions over the same time frame; they’ve essentially stayed flat: There are a lot of valid arguments on why this is happening, but I think we can all agree that this is not a great direction to be going in. Server Fault still gets a ton of bad questions, which need to be closed - and there are now fewer regular contributors among whom the load of “taking out the trash” is now spread. As a result, instead of participating through posting and voting on useful questions and answers, many of our most active users, the core of our community, are spending their time on the site looking for questions to downvote and close out of frustration. We don’t want our best contributors feeling like the most important contribution they can make is to find stuff to get rid of - and more importantly, we want to avoid deterring people from joining the community and participating by being over-protective of what we want the site to look like. Narrow interpretation of the scope with rigid enforcement hasn’t slowed the volume of poor quality questions, but it has given Server Fault a rather hostile and insular reputation and a tendency to give a poor first impression. I wouldn’t be comfortable telling a sysadmin I just met, especially a beginner or intermediate level one, that they should go try participating on Server Fault without warnings and caveats, and I suspect I’m not alone on that. We need those intermediate level people to be comfortable with dipping a toe into contributing, getting involved, to take the load of answering easy questions off of the veteran users who are tired of the simple stuff. This needs to be a place that’s welcoming of all system administrators, regardless of skill level, in order to accomplish that. Some of our veteran users will reduce or stop their participation, which is expected in any community; we need to have new contributors coming in to keep the community alive. More eyeballs from Google should be a good thing for Server Fault; it means that this resource we’ve all created is reaching and helping more people, and it means more people who might take an interest in the site (and have expertise that would be useful to have around!) are getting exposed to it. Instead, the we’ve taken a harder line than ever to fight the perceived flood of low quality questions. Server Fault should be a community that is welcoming of the easy questions. More importantly, it should welcome the kind of people who will be interested in answering those questions, who can can grow their own expertise while at the same time preventing our core contributors from having to deal with every easy question. It should be a community that changes and evolves alongside the practice of system administration, not one that gets stuck on a specific, rigid definition of what a sysadmin does or doesn’t do. It can’t survive and thrive and continue to be a great resource to so many people if we make it a community where only experts are able to ask a good question - after all, our experts are good at answering their own questions too, and rarely need to ask one of the community. Becoming more insular, more selective, more “expert”, is not an option that will lead to a sustainable future for Server Fault. We should be encouraging questions on subjects like Docker and continuous integration, about trouble with configuration or troubleshooting on specific blank-as-a-service platforms, and about how to architect a server infrastructure for the NoSQL flavor of the month. Instead of trying to reject these questions and the people who ask them, we should push them in the right direction for how to be better at what they’re doing and how to solve their problem in the right way. Getting that knowledge out there, in front of the eyeballs from Google, is how we can really make a difference. A few months after I started at Stack Exchange, the community team asked me to look at what I would do to try pushing Server Fault in the right direction. What I’ve arrived at is to remove the “professional” criteria from the scope of the site - it’s getting used too aggressively in closing questions, as well as interpreted to limit the set of topics that are accepted here. Now, before anyone panics.. What I’m about to propose isn’t intended to lower Server Fault’s quality bar, or open the door to everything that belongs on Super User being on-topic here. I’m asking for questions to be considered on their merits , taking away the close criteria of “infer whether this person has the right job title” because that can’t be what we’re focusing on when we decide if a question fits. We still want to make it clear that if it’s for someone’s home network, it goes on Super User. And if it’s a weak question that can’t be understood or has no detail, I expect the close-hammer to fall just as fast as before. However, someone having problems with setting up hobby project on a VPS even if they aren’t a sysadmin by day, or a developer trying to work out how to deploy their application successfully to a robust server stack instead of their development machine, are the kind of questions that I want to be in scope for the site now. This isn’t going to directly address the volume of low quality questions that we’re currently dealing with. What I’m hoping for is a change to the community’s approach to some of those questions: spending time editing the salvageable ones, giving users a push in the right direction instead of closing their question as quickly as possible in an attempt to avoid “broken windows”, or downvoting the question because they think the answer is too obvious. Removing the requirement to be a professional means telling these users “your question isn’t appropriate as it stands, improve it by...” instead of telling them “you don’t belong here because you aren’t what I consider to be a professional sysadmin.” Over time, my hope is that we attract more intermediate-level contributors that we’re scaring away now who can handle the easy questions so the veterans won’t need to. Question quality, and making sure contributors aren’t spending their time sifting through questions they aren’t interested in, is something that’s been getting a lot of attention on the Stack Overflow side of things, which can benefit Server Fault as well. Some of those efforts are applied here automatically, like rolling rate limits - we’re also going to test out how well some of the specific optimizations on SO work on SF, like the recommended tab , and see if we can tune them to work well here. I want for Server Fault to be the great resource to so many people that we all know it can be, and the great community that I’ve known over the last 4 years, and continue to evolve as a resource for everyone in this profession - and I believe that it can do that as a place for everyone working on the kinds of problems that we are, whether they call themselves sysadmins, SREs, devops, or anything else. My hope is that everyone in the community will join me in giving this a shot. | I'll be the first to admit that I've stepped away from SF for a while. Those reasons are my own, and everyone should be able to step away when they want to. That said, I've been looking at the site more recently, partly because it's been brought up in team meetings and partly because I miss answering questions and helping people. This is not the community I have great memories of. This is not even the community that I left. This is now a community full of hate and isolationism. Personally, I was very disheartened to come back and see that state that this community has changed into. We are not helping to make the current, future, and past generations of system administrators better here. People should not be shouted down because they are perceived to be not good enough. New people to our profession should be welcomed with open arms, taken under our wings and taught how to become a good admin in today world. We all had basic questions when we where young admins and there were people who guided us. Now that we are sitting at or near the top of the mountain, all we are telling the people who are not as skilled as us is you are not good enough, you are dumb, go figure it out for yourself. For me, answering questions here, and on other forums in the past has been a way for me to give back to the community that made me the Admin I am today. To help mold the future so that our profession can come out of the dark basement, can be better than what we are now. If we continue to work the way that we have then all we are doing is killing this site, and driving the sysadmins of the future somewhere else. And I believe the SE network is the best place to get amazing answers to your questions (not just because I work here, I believed that before I was hired). | {
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7,919 | I am building a command line script (Linux-based) for which I have a Dockerfile to define a Docker container within which I do testing etc. I have a question about why the HOME directory is not being set/used in the way I expect within the Dockerfile. Would this be on topic for ServerFault (because the question is about Docker, and hence "server administration" in that loosest sense), or is it more suitable for Stack Overflow? | I can't tell you if it's more suitable for SO or not, but the question you describe sounds like it would be topical on Server Fault, yes. | {
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7,925 | I have a simple question, per the title, that I'd like community feedback on before venturing over to Stack Exchange meta and/or bugging one of the Stack Exchange Community Managers . Should the rep requirement for creating tags on Server Fault be raised? (And if so, to what?) Currently, it's at 300 for Server Fault . By contrast, at Stack Overflow, 1500 rep is needed to create new tags . I think our threshold is too low, and believe that the lower threshold here is the reason that we have literally hundreds of garbage tags with only a handful of questions in them. Because I stumbled across them within the last few minutes, outbox , rotating and sender come to mind immediately as tags with absolutely no value that had one or two questions in them, and were created by users with low reps. (Not to say that all tags with few questions are necessarily garbage tags, but there is a strong correlation, from what I've seen in my retagging efforts.) I am of the opinion that increasing the quality of our tags, and maintaining a certain quality is important (otherwise, why have tags at all?), and that doing so would be greatly aided by increasing the minimum rep required to create them in the first place. I can go through and remove the hundreds of tags that ought not exist and have only a question or two in them, but that does little good if hordes of low-rep users come in behind me and decide to tag their questions with what are essentially 3 or 4 important words from their particular problem. Off the top of my head, I think I'd place the tag creation privilege at or near the tag synonym creation privilege, which is 2,500. <Sidebar> On the off chance the purpose of tags is not clear to anyone, tags exist to categorize and organize. We currently have over 5,000 tags. Over 1,000 of those have only a handful of questions (5 or less), and the median number questions per tag is approximately 16. To me, this indicates that at least a large number of our tags are of poor quality. IT is a huge field, but I find it hard to defend a categorization system which divides it into over 5,000 categories... and all the more when thousands of those thousands of categories only apply to a handful of questions out of the >180,000 questions we have on the site. The only explanation I have is that we have a very large number of tags that should not exist, because they are not actually IT-related categories. (To borrow from my bad tags thread, "fixed" is not a category related to IT. "Width" is not a category related to IT. Nor is "rotating," "outbox," or "social." Not even if the question is about fixing the width of your rotating inbox while remaining social with your co-workers. The problem with having large numbers of poor quality tags is that they defeat the benefits of categorization that tags exist to create in the first place. Searching through 5,000 categories is harder and more time-consuming than searching through 4,000, and if those "extra" 1,000 tags don't have any value, then you've just inflicted increased cost and effort on everyone for no reason. </Sidebar> Having said all that, what does anyone else have to say on the subject? I'm thinking I should request of the Stack Exchange CMs that the tag creation reputation threshold be raised to 2,500 for Server Fault. Yes? No? Too high? Too low? Don't Care? | Yes increase the reputation requirement to create tags. Most people with only 300 rep probably don't quite get how tags are supposed to work. People tend to forget or not know that spaces separate tags and where a - should be used or that they are sorted by popularity. For example the fixed and width you cite should probably be fixed-width and they could end up as width , fixed . There are plenty of other examples of this. I think 2500 is probably too high. Rep is hard to come by on SF perhaps 1000 or 1500 would be better. | {
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8,054 | Myself and a few others just noticed that HopelessN00b and Chris S are no longer listed as moderators . What is the story behind this? | Since HopelessN00b wants to have this discussion in public, I will oblige. I was on the site today because we got a few different emails this past week about it. One was Chris S, stepping down as a moderator - I'll let him talk about that if he wishes to; moderators are volunteers, and are of course free to step down at any time. The rest were complaints about actions taken by HopelessN00b. This is also not particularly unusual; we get complaints daily about moderators on all sites. Usually I spend a few minutes checking out the situation, a few minutes more explaining it, and everyone goes on with their lives. Instead, I found this: (actually I was looking at a different page that displays the last 500 comments, but the gist is the same: a wall of identical comment, posted in groups, each a few seconds to a few minutes apart) This is a bit worrying, but not entirely unusual - moderators or regular users engaged in a big cleanup campaign often have histories of repetitive actions. So I dug a bit deeper - starting with the links in the comments themselves, then in recent meta activity. Nowhere did I find any hint of a massive question cleanup campaign. Now I'm getting a bit worried, especially since these closures (and comments) are still appearing while I'm researching. I checked chat - both the public rooms associated with Server Fault, and the private moderator room. Nowhere was there any discussion of this, save for a lone message from Hopeless in a nearly-abandoned chatroom noting that he had been "closing webpanel questions by the hundreds". At this point, I'd already spent an unexpected amount of time on this, and from the look of things I'd be spending a lot more. And closed questions were still piling up; as a final sanity-check, I reviewed a sampling of them - some were obviously questions about administration panels, but this wasn't consistent; the majority of those I checked made no mention of such tools. Handling a rogue moderator When a normal member of the site starts making massive, controversial changes without prior discussion, the standard procedure is to immediately suspend the account in order to stop the bleeding, then discuss the matter. But suspending a moderator doesn't accomplish much. So the remaining option is to remove moderator status, and then attempt to discuss whatever is going on - if the situation can be resolved quickly, this need not be a permanent change in status; if the situation goes south, suspension is then an option. So I removed Hopeless's moderator status and sent him a message requesting that he explain the situation (the other Server Fault moderators were also copied on this message). I've yet to receive a response. Thus far, I've identified 572 questions closed with some variation on that comment over the past 2 months. The average score was 0.1, the maximum score was 19. The comment was replied to 29 times; Hopeless responded to 1 of them. These questions will need to be reviewed; Michael has started a separate discussion that will help determine the criteria which should be applied to them. Update 4/10/2015 After being asked to post this publicly, I finally got a response privately last night. It did not attempt to answer the one question I asked. I'll be going through server logs this weekend to attempt to determine what was actually being done here. So in summary, if you are a community moderator on a Stack Exchange site, here’s what to expect: As a moderator, your actions now represent the community, so you will be held to a higher standard of behavior. You are an ambassador of trust, with the same sorts of rights that the official development team and community coordinators have. That trust has been betrayed. I am extremely disappointed in how this situation has played out. I will be working directly with the remaining moderators to ensure that this community's standards are being upheld and communicated effectively, and that any damage is repaired. Update / conclusion: 4/13/2015 I've finished my analysis of Hopeless's activity as a moderator on Server Fault. This is a bit long; there was a lot of activity - more on that in a bit. For those of you who aren't interested in the details, the summary is that I was relieved to find that Hopeless has acted as an enthusiastic but largely competent moderator, serving the community here faithfully except when it came to responding to questions/concerns regarding his actions and in communicating his efforts in cleaning up old posts . Related to this, I've identified two areas where our tooling is deeply lacking and likely exacerbated the problem. Following his election in December, Hopeless was off to a good start: he handled a respectable portion of the flags raised here, participated in review, and participated actively on meta. The only oddity I found in his actions at the start was a group of 581 questions that he locked for Historical Significance in his first week; this is notable for two reasons: only 241 of them were closed prior to being locked, and that's more questions than had previously been locked in the entire history of the site. (for reference, historical locks are a bit special - it was added for "too big to fail" posts that were no longer allowed but too good to lose , and posts where it is applied disappear from the homepage and from normal question lists... So it's a bit hard to notice when it's being used - more on that later.) A good chunk of these were subjective polls and GTKY stuff from the very early days of the site - stuff like What's your favorite Linux distribution? or What is the best VPN technology to implement in a SOHO setting? ; it's hard to get upset about locking them, unless you're inclined to complain that they weren't just straight-up deleted. Still, this was a sign of things to come in that I can find no discussion of it anywhere . Then in early January, things started to get interesting : Hopeless started cleaning up tags. Starting with a set of web admin tags he'd identified back in September , and then moving on to a much larger group of tags . The week of January 19th he edited tags on 875 questions, closed 399, deleted 221, and locked 817; he then slowed down for a few weeks before breaking his own record during the week of February 16th with 988 tag edits, 262 closures, 546 deletions and 723 locks... and 1,513 tag merges. The locks and merges need a bit of explanation. In the big tag burning thread , he mentions using locking as a tool to prevent bumping too many questions to the homepage: questions that are locked for historical significance can be ?-edited (therefore, retagged) without bumping them to the top of the active list... so I'll be temporarily locking questions I retag to minimize disruptions. Not all of the locks were temporary; of the 2342 questions locked in January and February, 869 remain locked. The merges are harder to explain. Indeed, someone asked about them on February 26th , but didn't recieve any clarification. We discussed this in chat at one point, after I'd noticed the merges and complained; apparently, the idea was to get rid of the tags first by merging everything into [off-topic] and then go back through that tag and perform any necessary cleanup. It helps a bit to read this answer , in which Hopeless responds to a user complaining about a tag he was using being suddenly gone; if you think of tagging more in terms of a physical filing system rather than a folksonomy , the concern over having too many of them is understandable. January also marks the start of using a canned comment when closing questions, with the week of the 12th seeing a whopping 312 questions closed with: This question appears to be off-topic because it is about working with a service provider's management interface, such as cPanel . By late February, Hopeless had refined this message to its current form, and was using an app to integrate it into the moderation UI . Note that the question I just linked to is the only discussion of this I've been able to find, and concerns a newly-asked question. This becomes easier to understand upon realizing that a substantial portion of these questions were also being locked , at least temporarily - thus they would've immediately disappeared from all normal question lists, and their authors - although still notified of the comment - would be unable to respond to it. After the initial tag cleanups, Hopeless was relying less and less on tags to filter questions and more on keyword searches for the names of various web administration tools. He was still using [off-topic] as a filter for retagging, but by the week of March 30th retagging had taken a clear backseat to closing: 74 retags, 227 closures (95 of them coupled with the "webadmin" comment), 67 deletions and 74 locks. Last week saw 110 closures (79 webadmin), 82 deletions, 33 locks and 35 tag edits. To recap: this cleanup started with this meta post , where the only mention of closing is in answers noting that normal rules should be applied. It continued through a tumultuous tag burnination and transitioned into an effort to eradicate all mention of web admin tools from questions on the site. There was no discussion of this beyond the original tag cleanup; locking - though likely well-intentioned - obscured the scope of the effort for months. Very few others were involved in any way; a handful of people did participate in retagging, but the majority of the work - indeed, the majority of editing and moderation period - over the past three months have been the work of one solitary individual. A new off-topic reason was added via comments, without review by either the community or the rest of the mod team, and was single-handedly made into the single most-used close reason on the site, in the process avoiding both the guidance given to moderators for using off-topic reasons, and the restrictions built into the system itself for creating them : The moderator who created a reason cannot approve it himself; we want at least two people to be reviewing these before making them available. Approving a reason also activates it, and as noted above, only 3 reasons can be active at any one time on most sites - to approve more than this, an existing reason will have to be deactivated first. I believe Hopeless had good intentions here. But by playing the maverick, he left himself and the rest of us open to criticism and without a clear defense. If he had taken just a little bit of time to talk openly about what he was doing, if he had been more receptive to criticism, this all could have been avoided. The past couple of weeks appeared to be where things started taking a serious turn for the worst, so I went through and reopened 20-some questions closed during that period where any mention of web admin systems was clearly incidental. Some of the moderators have been doing their own reviews and reopenings as well. Going forward, we'll need to do a more structured review - at minimum, there are several hundred questions where historical locks currently prevent any attempt at community moderation; those should probably be removed before anything else. I'm open to suggestions on how to conduct a productive review of them. In closing, I'll add that doing this analysis has been an eye-opener for me: The guidance we give to new moderators regarding the necessity of communication is lacking. There's an introductory email that touches on it, and of course a whole lot of history on Meta Stack Exchange... But not everyone reads the manual. This stuff needs to be baked into the UI itself , particularly when... Extreme outlier events should trigger something. I'm still thinking about what exactly this should involve, but for sure quadrupling the number of locked questions on a site should cause something to happen. At minimum, it shouldn't go unnoticed by... High-reputation users need better information. The current 10K tools were adequate back in '09, but a lot has changed since then. At minimum, these folks should be able to review the number of posts being deleted (and for what reason) over time, the number of questions being closed over time broken down by reason (including custom comments!) and the number of locked questions independant of things like migration. And it's probably time to revisit the notion of bespoke review tasks for those situations where you really need to get a lot of folks involved in something like a tag cleanup effort. Or... reviewing 1500 locked questions. | {
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8,071 | First off, I know I said and take the weekend, but it turns out I don't need it, and it does seem like a dick move to let things keep going on as they have, when there's no benefit from doing so. As they say, when there's no new information to be had, it's time to make a decision. In this case, there's no new information that could come about to change my mind, so, same difference. Second off, Shog, I can't respond to your moderator message until someone responds first . Makes it hard to be communicative when I am actually being preventing from responding. A moot point at this point, but you've got my email if you desire further information on anything. I doubt I can provide you with anything more than what I've said already, but feel free to ask, should you desire. Finally, before I get into it, my apologies to everyone for the drama/fallout/whatever. Hopefully, this post will do something about cooling that off or preventing further dramatics. The events of yesterday and today have made it clear to me that I am not suitable to be a moderator for Server Fault, and not unrelatedly, that I do not wish to be one anymore, either. It doesn't matter who's right or who's wrong, the simple fact that my actions have created "friction" indicate that I no longer belong as a moderator, and that I don't belong here at all anymore, either. I understand everyone's point of view - the members who are insisting it's a good thing to be cleaning up the crap, the Community Managers who see my actions as unilateral or suspicious or detrimental, the members who think there should have been more discussion or oversight, before I took it on full-bore, etc. The problem is, for me, that there's a question, or concerns at all about me (or even any high-repper/old-timer) re-tagging and/or mod-closing (etc.), is an irreconcilable problem. As I see it, this has all been discussed at such length, with such overwhelming community consensus that I'm sick of hearing it. We've got an indescribably massive pile of content that needs reviewed, the active community is now so small that there aren't enough people to do it, so fine, I'll step up and do it, no possible way that could be a problem for anyone. Except that it was. Reviewing literally thousands of low-quality or off-topic or just plain bad questions (and probably easily into the tens of thousands) is enough of a chore without having to talk about doing it too, especially when I've been in that discussion dozens of times. If that's what it takes, I don't want to do it. And to find out that all this effort was for nothing, for less than nothing, seeing that it caused this drama, gave the Community Management team headaches, and didn't even make the site appreciably better as a result... well, damn, I clearly shouldn't have bothered in the first place. In fact, what the hell am I even doing here? I've been trying to keep the tide from coming in with a toy shovel, and the whole time, I wasn't making anything better, I was just wasting my time and spraying sandy salt water in peoples' faces. The Server Fault that's a community for professional systems administrators to congregate around doesn't exist, and I cannot make it that way, no matter how hard I try. This is all probably something I should have known 2 years ago, when I took a ~9 month break from the site, or ~9 months later when the only thing that brought me back was the now absent denizens of the Comms Room, or when I decided to run for mod to prove that I wouldn't get elected, or when I actually did get elected, or when the core of the community packed it in and abandoned the Comms Room for pastures unrelated to Server Fault and Stack Exchange, or on any one of countless days when I've had to "quit Sever Fault for the day" because I couldn't bear to see one more piece of crap posing as a question from some inconsiderate jackass moron treating this site and everyone on it as a personal answer machine happy to accept his typed-out diarrhea. But I didn't. My bad, and my sincere apologies for the resulting fallout from the last couple days that are ultimately a result of me being too stupid and stubborn to accept what should have been obvious to anyone with half a brain, paying the least little bit of attention. I am extremely grateful to Server Fault (and to Stack Exchange for making Server Fault possible) for all it's done for me, but the painful truth is that the Server Fault I joined, contributed to, learned from, and met a wonderful group of systems administrators through no longer exists, and trying to make it exist again is no good for anyone. Time for me to move on and make way for what comes next. | The biggest problem I see here is that Stack Exchange is showing that they do not trust democratically elected moderators to do what they were elected to do. We, as a community, elected HopelessN00b to be one of our leaders because we knew he would be willing to do the one thing that he got spanked for... cleaning up junk questions that didn't belong on this site. And the defense of "well, he didn't discuss what he was going to do first" is 100% invalid. We, the members of the Serverfault community, have all been discussing for years how bloody cPanel (and the like) have no place here. To have a stranger walk in and let us know what we have and haven't been talking about is, frankly, insulting to all of us. I don't know why anyone would want to be a moderator, now. | {
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8,094 | My question was closed as off-topic because it is "about a web hosting control panel". But I still need help. Where can I ask my question? | Unfortunately Server Fault is unable to support web hosting control panels for a variety of reasons . But you may still be able to get help at: Your Service Provider If you are using a web hosting resource (e.g. shared hosting or VPS) provided by someone else and need help with the control panels to manage it, first contact your service provider. If the service provider is unable or unwilling to help, continue on: Vendor Support Generally you should first seek support from the vendor of your control panel. They know their products best and will be able to give you the most appropriate help. The support pages of the most popular control panels are available: cPanel/WHM DirectAdmin ISPConfig Kloxo/HyperVM Plesk Sentora ServerPilot VestaCP Virtualmin ZPanel Stack Exchange Some Stack Exchange sites may also be able to help you with your question. Webmasters may be able to help you with questions about running your website. Unix & Linux may be able to help with questions about Linux and Linux applications. Web Hosting Industry There may be other forums and community resources you can visit. A small sampling of these follows: Digital Point Forums has a Site & Server Administration section. Web Hosting Talk has a Hosting Software and Control Panels section. | {
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8,410 | A simple yes or no question: Are questions about legacy products inherently off-topic? For instance we regularly get new questions about windows-server-2003 which ran out of extended support in July 2015. If even the vendor no longer provides support, why should our community? | No, each question should be judged on its own merits. Although we all agree that life-cycle management is important, its is also difficult. Good questions about legacy products are welcome. | {
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8,456 | Should the administrator tag be nuked? | Yes, nuke it. Bump: I've started the cleanup of this tag. If anyone else would like to assist, please feel free. Please perform your edits in small batches so that the front page doesn't stay inundated with these edits. | {
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8,549 | This has happened to me several times already, and I think I'm not the only one. A (possibly new) user comes by with a question which clearly shows he is way out of his depth and he needs professional advice, such as this one ; after some comments and/or answers, the suggestion is given to hire someone who actually knows what he's doing, and the question is closed as too broad and/or not professional enough. The user will probably realize the truth in the suggestion, and he'll go find someone with real experience. Now, chances are one or more other users could actually help him, and are willing to do so (for a price); case in point: I'm an expert in network design (amongst other things) and I'm currently unemployed, thus a short-term consulting job like "please advise me on designing my company network" is something I'd be glad to take on. However, I have no way to contact the user (there still is no PM function on any StackExchange site), and posting my email address in a comment is something I'd like to avoid; also, posting a comment such as "please contact me privately, I could do this job for you if we agree on the price and terms" strikes me as rather inappropriate for a site whose main purpose is definitely not handling job offers. So: there is a situation where a user is clearly in need of professional support, he is probably looking for it, and someone is willing to take on the job, or at least tell him "let's see if we can work together on this". But the site provides no means to handle this situation. What would be the best approach using the current tools? Could something be introduced to handle this better? | Agreed, this is a touchy subject, and I appreciate that you are bringing it up. There are many barriers in place: both technical and ethical. Technical, in that we don't have a PM feature, and ethical, in not wanting to spam SF QAs with consulting solicitations. As a mod, I'm also (perhaps needlessly) even more careful to not solicit consulting gigs than I would be if I weren't an elected moderator. Anyway, I have chosen to post one of my "junk" email accounts on my SF profile. While I never solicit work, people do contact me from time to time at that email address, and I've done a small amount of consulting work as a result of those contacts. In your case, I would either recommend either doing as I do, post a junk email account, or else leave a comment for the user to the effect of "post your email somewhere and I'll contact you". Clearly, if someone started soliciting work incessantly on posts, they would likely get dope-slapped fairly quickly, but I would have absolutely no problem with people like yourself trying to connect with people from time to time, especially in instances like the question you linked to, where guidance is clearly needed. | {
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8,696 | It turns out the the recent question regarding the misuse of rm -rf in Ansible was actually just a hoax ( English ) in some kind of viral marketing effort. It become quite famous on various media and gathered a large number of views. Since I don't think we should allow ServerFault to be abused in such way, I deleted the question once I learned about the hoax. However, this will rob the kind people that took the time to answer him of the rep points they earned for this, in particular the Journeyman Geek with 185 upvotes. So, how should we deal with this question? Vote below. There is a clear majority towards merging the question into this one . I'll do this now. | It was closed as a dupe. Delete the hoax and keep the dupe. Consider merging the answers from the hoax into it. Remember SF is for practical problems you are trying to solve. A hoax by definition isn't this. | {
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8,740 | A large bulk of users with 1 rep ask remedial vague and constantly reoccurring questions, many are not down voted and some are answered. aren't we enablers for laziness? it seems to be acceptable usage of SF. When things are documented better elsewhere and are easy to find - shouldn't we just tell them to RTFM and do our entire industry a favour? | If the questions are of a low quality, they should be downvoted and/or closed. You haven't linked to any of the questions you consider remedial, but I'm assuming that you mean ones that show little or no research effort and that are very basic. The very basic ones can be closed as off-topic with the following close reason: Questions on Server Fault must be about managing information technology systems in a business environment. Home and end-user computing questions may be asked on Super User, and questions about development, testing and development tools may be asked on Stack Overflow. If the question is not otherwise bad, and it's about Unix, you can vote to move it to Unix/Linux . You can also vote to close with a custom reason, where you are free to write what you want. Here's an example: This question is being voted for closure because the author does not show a level of technical understanding or appropriate due diligence in researching the topic that the community judges as being a minimum barrier to participate. | {
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8,743 | My question about whether Amazon CloudFront offered DDoS protection was put on hold as off-topic because I was allegedly asking for "product, service, or learning material recommendations". I was clearly not asking for recommendations or opinions. Amazon CloudFront offers DDoS protection or it doesn't; and if it does, it could do so at different layers of the OSI model. The answers must be objective. Another user didn't like the fact that I was referring to a commercial service, which seems perfectly fine according to what's considered on-topic here . Plus, the question was put on hold so that I can reword it -- And however I do that, I'd always be referring to the same commercial service. I'd really love to know if I did anything wrong so that I can keep it in mind in the future, or if my question was appropriate, I'd appreciate it if it could be reinstated. | If the questions are of a low quality, they should be downvoted and/or closed. You haven't linked to any of the questions you consider remedial, but I'm assuming that you mean ones that show little or no research effort and that are very basic. The very basic ones can be closed as off-topic with the following close reason: Questions on Server Fault must be about managing information technology systems in a business environment. Home and end-user computing questions may be asked on Super User, and questions about development, testing and development tools may be asked on Stack Overflow. If the question is not otherwise bad, and it's about Unix, you can vote to move it to Unix/Linux . You can also vote to close with a custom reason, where you are free to write what you want. Here's an example: This question is being voted for closure because the author does not show a level of technical understanding or appropriate due diligence in researching the topic that the community judges as being a minimum barrier to participate. | {
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8,934 | The question that got me wondering about this is here: Displaying nmap result gradually as results are found The answer to the question is directly quoted from the nmap man page. I was tempted to flag the question for closure, but the question is well written and technically on-topic. | RMaaS (Reading Manuals as a Service) is part of our community services... Although I often comment with: Server Fault is a site for information technology professionals -- as such we have certain professional expectations when people ask a question here, and one of those expectations is that you will have done some research , found and read the vendor documentation and/or tried a solution before asking the internet for help. ... We also have the motto : Good questions get good answers. So if the question does not make your eyes bleed and your more advanced experience allows you to more easily find the relevant answer in the manual and you're inclined to answer, please don't hesitate just because of that. ( Please don't forget to include the correct attribution when you quote a section of the manual verbatim. ) Fairly often the reason I can point to the manual in the first place is only because I already know exactly what keyword/jargon to look for and where . Simply starting on the first page won't easily get you there. I.e. try searching the 57 separate man pages that make up the terse OpenSSL manual or search the Bash manual for the meaning of . (a period) in shell scripts... | {
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8,966 | I have been spending a lot of time Serverfault lately trying to first educate myself, second see if i can be helpful and thirdly bring up my own reputation. I notice 2 things: When a user with a low reputation asks a question there seems to be a good amount of views however no answers. I kind of see a couple of these questions as low hanging fruit being some are basic question that even I can answer. Even though my answer is the only answer and i had been talking with the user through comments and im pretty sure I have answered the question they do not mark it as correct. Really feels like a waste of my time, and Im thinking that a lot of people have already learned this being that my 1 answer is the only one there. Not even comments. Is there an unspoken rule i am missing or maybe its time for the moderators to think of a system of maybe forcing people to get to X reputation before even being able to ask a question. I know this sounds harsh however it might keep the people who really don't want to learn and are looking for free help off the site and let the professionals keep learning. Without rambling on too much more, I know not really a question here but it kind of grinds my gears. Just my thoughts. Any feedback or thoughts would be appreciated. | There's a few things at work here: You're right that some people avoid answering questions from low-rep users because there's a good chance that the asker won't give any sort of feedback. Personally, I long ago let go of my craving for UIP ("Useless Internet Points") and I've been happier ever since, but I know it's a concern that some people have. Plenty of "old hands" have given up answering "n00b" questions because they're boring and repetitious. That's pretty much the boat I'm in these days -- I'm just not that interested in explaining some basic concept yet again. I might point to a canonical question if I'm feeling generous, but usually the expectation I'll end up arguing over why the canonical question does have the answer, if the asker will just engage their thinking organ for a little while, usually dissuades me. A lot of questions from new users are poorly thought out, incomplete, muddle-headed, or otherwise deficient in some way that can make it frustrating to answer, so for people who are already jaded and cynical, dealing with another round of "what are you really asking?" can seem like too much effort. There's an upside to all this for you, the eager newcomer to our fine corner of the Internet: there's lots of questions that are just crying out for your care and attention. As long as you can avoid falling into the trap of thinking you "deserve" upvotes and accepted ticks (and the bitterness that results), answering questions can be very rewarding. You learn all sorts of things about how to ask good questions, think through a problem logically, communicate ideas clearly, and personally, I've found I need a much better understanding of a topic to explain it than I would if I were just "doing" it. As for the suggestion that people get a certain rep before they can ask a question... it's been suggested before. At one time or another, I may even have made such a suggestion (or supported it) myself. The problem with it is that a Q&A site needs both questions and answers. While it's certainly true that ServerFault, at least, currently has a problem with the endless September of bad questions seemingly driving away all the people capable of providing answers, I'm pretty sure that if we made people jump through rep-gaining hoops (which basically means "answer questions") before asking, it would drive away an equal proportion of "good" questions as it does "OMFG srs?" questions. I don't think it would have the desired effect, unfortunately. | {
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9,044 | I by no means consider myself to be a professional network administrator. Rather, I am a systems and application programmer, and an occasional project manager. However, due to the nature of my work, I am sometimes forced out of necessity to take on at least some roles that would normally be in the domain of a professional network administrator and technician, especially early on in a project's timeline. Often times it requires significant research effort on my part to make sure that I am doing at least a decent job, since I have neither formal training nor significant experience in the area. The projects tend to be unique and highly specialized. As such, the questions I have often deal with "professional" level networking scenarios, but I have only a novice/intermediate level of knowledge. Essentially, they're amateur questions in a professional context. Is it acceptable to ask amateur questions here if the situation is, for example, not a consumer-level networking setup, despite the fact that I am not a professional network administrator? In other words, can non-professional administrators still ask questions about professional setups? I don't actually have any specific questions in mind otherwise I'd give an example, but on multiple occasions in the past I have thought about this site while searching for information, but stayed away out of uncertainty in an attempt to respect the topics here. | I am fine with this, as long as: The systems and equipment are truly professional-grade. (No questions about Aunt Mabel's inkjet printer) You have full administrative permissions on the systems you are asking about, and have the authority to modify their configuration. You have attempted to resolve the situation on your own, and can provide evidence to us of this - what worked, what didn't work, etc. The more details you can provide, the better. You are not asking us to explain rudiments to you. For instance, asking a question about how a router works is not acceptable. We try to not be fundamentalists here. Yes, we are a site for professionals, but even if you're not that, provided that you can satisfy the above requirements and you are fulfilling the role of a professional, go for it. | {
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9,618 | A few months ago I took a break from moderating and participating in SF for reasons mostly unrelated to today's post. I am not entirely 100% satisfied with the way that turned out, but I am cautiously optimistic that SO can recover from its mistakes and rebuild trust between it and the community. But that is not why I'm posting today. Between then and now I was diagnosed with stage 4 colon and liver cancer. I have already had one surgery and there is more chemotherapy and surgery ahead of me. As a result of all this, I am going to need to devote time to focusing on my recovery, however long it takes. I will not be able to return to moderating Server Fault at any time in the foreseeable future. I have already advised the community team to go ahead and remove my moderator access, and the diamond may be gone by the time you read this. Since I first joined in 2012, I have found SF to be an amazing community with some of the smartest, most competent sysadmins on the planet. I am honored to have learned so much from you all and I have been glad that I could make my own small contributions. Over the next few weeks, as time permits, I will gradually begin to return to reading and participating in the site as an ordinary contributor. I look forward to seeing you all again. | Michael, I am truly saddened by your news but heartened that you are able to deliver it to us yourself. I hope that your continued treatment works, is not further complicated by the Covid-19 crisis and that you are returned to good health. I've learned so much from your participation here at ServerFault, I hope to learn so much more. Thanks and Good Luck Iain | {
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9,680 | We're excited to announce that Octopus Deploy will be sponsoring Server Fault for the next year beginning very soon! These types of partnerships that help us bring more resources to our communities would not be possible without your hard work and dedication and we're extremely thankful for and proud of everything that you've done and continue to do. You've got questions about what this means, we're sure - and we're here to answer 'em! We've anticipated a few which we'll explore below: How will the sponsorship be displayed? Good question! The sponsorship will be shown in top right of the header of the site in a manner that's similar to the mockup below: The color of the logo might be different, we're still working out the final details, but it will be subtle and unobtrusive. Octopus Deploy will continue to run ads in existing ad spaces on Server Fault during the sponsorship period. What else changes? That's easy: absolutely nothing. Quoting from the MSE post linked in the introduction: First — sponsors do not own these Q&A sites. Sponsors work alongside our communities who ultimately build these sites. Communities ask the questions; communities create the tags; communities conduct elections as they do now, and we are not renaming our current sites like a garish sport stadium to the highest bidder. Any ads a sponsor submits still have go through our crazy-strict ad editorial process… as it has always been. Companies do not have access to personal data, and all Q&A content remains irrevocably licensed under Creative Commons for sharing and attribution. Sponsorships are a tool that our clients can use to let folks who would be interested in their products know about them. When does this start, how long does it last? The exact launch date is yet to be precisely determined, but we're aiming for the first week of November, if not a few days sooner. The sponsorship period last for a year from the date we go live. I think I found a design glitch / bug. Please report it as a separate bug . Thank you! I have another question or concern. Leave an answer below (I know it might seem odd to leave a question as an answer) and we'll do our best to answer you. Thank you again, everyone! Again, this would not have been possible without the huge amount of work you've all put into making Server Fault so successful. | Hi Server Fault community, I’m the founder of Octopus Deploy. I’m a developer by background and started Octopus in 2011 as a project in my spare time. We’re bootstrapped, not VC funded, but we have grown to the point of employing 75 people. We’re mostly an Australian company but employ folks in the US and UK too. I won’t insult your intelligence - we’re obviously sponsoring the site in hopes it will raise some awareness of us and what we do, particularly in the IT Ops space where I think we are doing some innovative things. We don’t have any full time marketers at Octopus, just myself and a couple of other technical people who I roped into dabbling with marketing from time to time, trying to raise a bit of awareness. In fact I edited the logo image for the sponsorship and designed and wrote the ad copy (and most of the website copy) myself because we really haven’t figured out how to “do marketing properly”. Part of the reason we like sponsoring Server Fault is that if we’re going to advertise (and the techie in me still struggles with the idea of advertising), we’d rather do it on actual technical communities rather than random sites based on all the data Google collects about you. In other words this feels like the most ethical kind of advertising option. I have personally found Server Fault useful many times in the past (I still code) and while I haven’t posted here much, I was pretty active on Stack Overflow years ago. A number of folks on our team hang out on various Stack Exchange sites too. We know that this is a community, not any ordinary website. We’re going to run a competition inside our company, with a prize for whoever can earn the most upvotes on our team on Server Fault by answering questions. We have lots of smart technical folks so I am sure they will be good quality answers. Hopefully this is a way we can give back to the community (or make our contribution somewhat neutral at least ). If you think this is a bad idea or see it causing issues let me know. I really do hope our ads aren’t distracting or offensive (more than any other ad at least). If there’s anything about what we’re doing that you have a concern about, post here and I’ll keep an eye on the thread, or email me directly - my firstname.lastname at our web domain. Thanks. | {
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1 | I've been building IPsec VPNs for years but to be honest I've never fully grasped the technical difference between IKE and ISAKMP. I often see the two terms used interchangeably (probably incorrectly). I understand the two basic phases of IPsec and that ISAKMP seems to deal primarily with phase one. For instance, the IOS command "show crypto isakmp sa" displays IPsec phase one information. But there's no equivalent command for IKE. | ISAKMP is part of IKE. (IKE has ISAKMP, SKEME and OAKLEY). IKE establishs the shared security policy and authenticated keys. ISAKMP is the protocol that specifies the mechanics of the key exchange. The confusion, (for me,) is that in the Cisco IOS ISAKMP/IKE are used to refer to the same thing. By which I mean, my understanding is that Cisco's IKE only implements/uses ISAKMP. So one configures IKE, and then conceptually inside that, one configures ISAKMP. | {
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5 | I know that to secure OSPF you should 1) use OSPF authentication, 2) use passive interface command on interfaces that do not have ospf neighbors. If I only use the passive interface command and not ospf authentication, what vulnerabilities am I left open to? | One issue is that authentication ensures that only trusted devices are capable of exchanging routes on the network. Without authentication, you could introduce a non-trusted device and cause significant routing issues. For example: If area 0 is not authenticated, attach a router in area 0 with bogus routes to null0. You could even create a default route and inject it into the topology leading to the bad router to black hole traffic. Or the route could force traffic toward a bogus gateway designed to sniff connections and pull out insecure data before sending it on the right path. Authentication ensures that only routers you know about and trust are exchanging information. | {
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16 | I was doing some cisco exercises on configuring a vtp server and client, something I can't figure out is : I setup a vtp server, added my VLAN's I then took another switch that was attached to this vtp server and set it to client Now my VTP client didn't get the vlans configured on the vtp server,
however when I added another vlan on my server, suddenly they were
all there Is there a way to push the configs, like a force update command ? | You can't manually force updates because VTP configs are pushed based on the highest current VLAN database revision number. Normally, after every change to your VTP config the configuration revision number should be incremented. The only way to force update this is by actually doing a VTP database change. | {
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83 | If an engineer configures some changes in a JunOS box and then set them to go live later, that effectively locks the config database with a configure exclusive. How can I see the changes that he or she has committed? | I think, you can use show | compare from configuration mode. | {
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99 | These days both fibre and twisted pair are supporting 1000BASE-T and 10GBASE-T, but when do you choose one over the other? The obvious one is maximum cable length, but what are other factors which might come to mind when making this choice. | There are a fairly large number of factors to consider and it is also important to accept that not all fiber is the same just like not all twisted pair is the same. Here are a few things that occur to me. Of course these may vary depending on environment. Fiber: Much longer max distances, depending on specification and throughput. No electromagnetic interference. Note however that fiber comes in a large number of grades and planning for the future may be somewhat more complex. Copper: Shorter max distances per link. Susceptible to electromagnetic interference. Fewer number of grades/variations (but still mind these!) meaning fewer accidents when the rollout team grabs the wrong spool (see below for a funny story). Supports power over ethernet. Funny story: A particular county in a Western state runs a fiber network that began as a control system for their hydroelectric dams. As time went on they found they didn't need nearly as much fiber as was laid for this and so they separated out many of the strands and used it to build a county-wide network linking homes and businesses to ISP's and telco's. Of course single mode fiber was used for longer transmissions and multi-mode for short runs. So when they were running the longer runs to connect towns and cities with this new network, the team that ran the fiber grabbed the wrong spool, and ran multi-mode fiber on all these long distance links. The team was quite unhappy when they found out they would have to re-run all the fiber again! Moral of the story: be very careful about ensuring that everyone knows which grades of fiber go where.... | {
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114 | How does STP/RSTP determine which bridge is the root bridge, and how are paths to the root bridge selected? | Not sure how much you know about switching and spanning tree but basically when starting out all switches claim that they are the root. All switches send BPDUs (Bridge Protocol Data Unit) which contain a priority and the BID (Bridge ID). The BID is 8 bytes long. 6 bytes is used for the MAC address of the bridge. 12 bits is used to indicate the VLAN, this is called extended system ID. 4 bits are used to set the priority. Lower priority means it is preferred compared to a higher. The priority is set in multiples of 4096. If there is a tie in priority then the lowest MAC address will determine which bridge becomes the root. To select the path to the root the cost to the root is calculated. As the BPDU travels from the root downstream the cost is increased INBOUND. 802.1D-1998 (legacy STP) had a cost of 19 for a FastEthernet interface. The newer standard 802.1D-2004 defines a cost of 200000 for FastEthernet. If there is a tie in cost then choose the BPDU that came from the switch with lowest BID. If that is a tie as well (multiple links to same switch) port ID comes into play. The port ID is from the upstream switch as well and consists of a port priority and port ID which identifies the interface. The default port priority is 128. There is a lot to spanning tree but these are the basic steps. | {
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119 | I'm comfortable with IPv4 address space allocations. By which I mean: Given services to plan for, or an organization to network, I have a good grasp of how to plan IP address space usage. (or at least, I think I do. :) Are there any best practices guidance, or case studies, for IPv6 address space layout? | The layout that we are using for our rollout is: /48 per customer /56 per customer site (as a subnet of the other /48) /126 for all point-to-point links in the core, these are all subnets of a /48 used for all core links These sizes are mostly taken from the RIPE advisory here . | {
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123 | Depending on what type of traffic is going over the network, it's often not feasible that an employee brings a wireless router and sets it up into your network. This is because often, they are not or poorly secured and present a backdoor into the network. What can you do to prevent rogue wireless access points being introduced into your network? | Lucas's answer above is a bit of a starting point. There are however two or three other things that must be considered. These end up being somewhat outside the scope of network engineering, but certainly have impacts for network engineering and security so here they go. You probably want some way of preventing wireless cards in company laptops from being switched into ad hoc mode. Assuming the laptops are running Windows, you probably want to use a GPO to set to infrastructure mode only. For Linux, it is harder to fully restrict, but there are ways to do this too. Enforcing IPSec is also a good idea, particularly with good key management and trusted enforcement. For example if you can go to X509 certs for key management this can keep unauthorized devices from communicating with the rest of your network directly. Consider key management as a core part of the infrastructure here. If you use a proxy server you may even be able to block unauthorized devices from accessing the internet. Note the limitations of your efforts. None of these prevents a person from setting up an unsecured wireless access point connected to a USB NIC, for sole purposes of communicating with their computer, especially if the SSID is hidden (i.e. not broadcast). Not sure how to further contain problems or if further paranoia is well past the point of insufficient returns..... | {
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130 | I understand that IPv6 reserves the fe80::/10 prefix for link local addresses, and that hosts select an address with a /64 prefix. Why is the reserved space so much larger than what is actually used for link local? | I think the link-local scope was set to /10 simply to "fit in" better with the other scopes, e.g. site-local (before it was replaced with unique local). Initially I had thought maybe it was to allow the use of many link-local networks on the same link, but RFC 4291 explicitly states that only fe80::/64 may be used. | {
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135 | I need to set up a modest iSCSI SAN with a few ESX hosts and one storage array. Can I get by using a Catalyst 2960-S or do I need to upgrade? Are there any special tweaks I need to make to the switch in order to handle iSCSI? The switch will be dedicated to the SAN; no other traffic except management will be present. | Given that the Cat2960-S is a desktop/access switch, with very, very small buffers, you would likely experience a lot of output drops. A datacenter switch, such as a 4948E, would be a better choice for an iSCSI application. To understand the reasoning behind this, you have to remember that an ethernet switch is either transmitting, or not transmitting on a specific port. If traffic arrives on port 1 for port 2, and port 3 is already sending traffic to port 2, the traffic from port 1 has to be buffered until there's a gap in the traffic from 3 to 2. If the buffer fills, additional traffic will be dropped. The term "microburst" is used to reference traffic that, over time, is well below the limit for the interface, but occasionally bursts to cause output drops. I am not as familiar with the 2960-S platform, but enabling QoS (without extensive tuning, see comments below) on it would probably be a bad idea; that would actually increase the number of output drops. Enabling QoS splits your very small buffers into 4 even smaller buffers, and most traffic will hit only one of them. | {
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147 | EIGRP and OSPF are both IGP protocols, the former is a mostly Cisco protocol and the latter is a well established open standard. What are the benefits of one over the other? Put another way, when deploying a network, why choose one over the other? If you have mixed devices the choice would obviously be OSPF, but what if you are running a Cisco only shop? Are there any features where EIGRP excels compared to OSPF that would make it feasible to only deploy EIGRP? | EIGRP is now an IETF draft so it's no longer proprietary. See https://datatracker.ietf.org/doc/html/draft-savage-eigrp-01 If we look at EIGRP with default settings and OSPF with default settings and there are multiple loop free paths to a destination then EIGRP will converge much faster because it keeps what are called feasible successors in it's topology database. These are basically loop free alternatives to the best path. EIGRP also has summarization at any point in the network. It also has stub feature which is useful when you don't want to use a router for transit. Commonly deployed in DMVPNS. EIGRP is also less confusing than OSPF because it does not have different network types and EIGRP is easier to deploy in hub and spoke scenarios. EIGRP uses a flat network without areas, this can both be an advantage and disadvantage. OSPF is obviously an open standard so it's the logical choice if you have multiple vendors. It can perform well but it requires that you tweak SPF timers because by default in IOS there is a 5 second wait before running the SPF algorithm. OSPF uses areas which means you can segment the network more logically. OSPF can only summarize between areas. OSPF is link state so it has a better view of the entire network than EIGRP before it runs the SPF algorithm. Network administrators will usually be more comfortable with OSPF because it's more commonly deployed. Both protocols have advantages and disadvantages. But the common answer that EIGRP should be discarded because being proprietary is not entirely true any longer. | {
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204 | Maybe I am missing something rather basic, but I don't know so I figured I would ask. In terms of testing, how sensitive various TDMoE are to BER and packet delay, I am looking into how to simulate delay and random packet dropping at the ethernet level. For these tests, I will probably just run iptables as documented in a similar StackOverflow question. However, although that will work here, I am not sure it will work in a more general case (perhaps testing BER tolerance between Windows servers and the like). So this has got me thinking. Are there any inexpensive network testing devices that allow one to artificially delay or drop packets in order to stress test protocols and evaluate sensitivity to latency and packet loss? My requirements are to be able to do this on the ethernet level. I am not looking so much for specific devices, brands, etc. so much as "are their things that do this?" and if so, maybe some general ideas of what they are like. I am mostly looking at building a simple bridge running Linux and iptables to do this. Just wondering if this is the right way to go. | There are tools like WANem which allow you to simulate WAN links by artificially causing arbitrary delay and loss rates on a link. WANem works at a relatively high-level; you won't see physical errors on the link but packets will be dropped. It can be deployed on commodity hardware. I know there are a few other tools which serve similar purposes but I can't recall the names of any at the moment. | {
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259 | As everyone is aware we are out of IPv4 addresses and soon (if not already) we shall be moving on to IPv6. What are some good strategies and practices to migrate a complete IPv4 network onto IPv6? | I don't have a full strategy, but here's the rough way I did it at $JOB[-1]: Get an IPv6 block, either from your existing carrier, or an RIR You might also want to mark a fc00::/7 (Unique local) block for fully internal subnets if you have an ISP block and may ever need to renumber Decide on your v6 IGP, IS-IS is still a safer option than OSPFv3, but much kit won't do IS-IS Bring up v6 on your core kit, from internet edge through to DC core switches Bring up v6 transit, if you have to a BGP tunnel from he.net can work while waiting for ISP's stuck in the last decade (remember to enable v6 on your iBGP mesh if you have one) Create v6 infrastructure services, mostly DNS, v4 accessible is fine here Enable v6 on a single server net (you'd probably have a default deny firewall here) Test the v6 connectivity to the world, will it break things? Turn up v6 on a second server net for redundency Bring up a DHCPv6 server if you want to use it Bring up v6 on a single access network (IT staff is a good choice here) Test. Ensure nothing breaks Bring up v6 on remaining server networks Add a v6 namesever for your domains, and a v6 DNS entry for an MX (one, or all but one are good choices for what to dual-stack) Now, when bringing up new services or upgrading them you can test if they work on v6, and add the appropriate DNS records (almost all web services will "just work"), eventually you might start looking for services remaining on v4 and fix them, but there's no hurry for that. | {
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412 | I've been looking at a hardware network tap like this one to replace a pseudo-permanent SPAN that's been running on a Catalyst switch. All the taps I find have four interfaces: A, B, and two output ports (one for each direction). Ideally I would prefer to funnel the traffic from both directions into one cable so I only have to capture from one interface. Why do taps always seem to have two output ports? | Hardware network taps provide one output port in each direction to ensure that traffic can be replicated at line rate. For example, a 100 Mbps Ethernet connection provides a theoretical maximum of 200 Mbps of total bandwidth; 100 Mbps in each way. If you tried to capture traffic from a line which was carrying 75 Mbps in each direction, you would need at least 150 Mbps of one-way bandwidth: more than a single 100 Mbps connection can carry. Hence, taps include two output ports operating at the same speed as the line being monitored. | {
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456 | Is there such a thing as a network bridge or is it always meant as a switch implementing a bridging function? Whilst bridges are described as devices that create separate collision domains in network specifications and tutorials, I have never been able to find any concrete product denominated 'bridge'. | Bridges as a product no longer exist due to how the market evolved. Typically the products specifically called bridges were used in hubbed environments to separate the collision domain or to bridge two network media types together (for example, Ethernet and token ring). Bridges as a function are definitely still around. Simply speaking, as a function of separating the collision domain, a switch is a bridge with lots of ports. For an example of bridging two network media types, access points are bridges that bridge 802.11 traffic to Ethernet. | {
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493 | When cabling a network using fibre, what is the difference between single-mode and multi-mode fibre? When should I be using one or the other? Are there compatibility and/or speed concerns with either? | Main difference:
Singlemode fiber has a lower power loss characteristic than multimode fiber, which means light can travel longer distances through it than it can through multimode fiber. Not surprising, the optics required to drive singlemode fiber are way more expensive, especially considering any varying circumstances. When to use each:
Both singlemode and modern multimode fiber can handle 10G speeds. The most important thing to consider is the distance requirement. Within a data center, it's typical to use multimode which can get you 300-400 meters. If you have very long runs or are connecting over longer distance, single mode can get you 10km, 40km, 80km, and even farther - you just need to use the appropriate optic for the distance required, and again, the prices go up accordingly. Compatibility issues:
They are not compatible. You cannot mix multimode and singlemode fiber between two endpoints. The optics are not compatible either. There's a lot more to say about fiber, in general, but I hope this answers your immediate question. | {
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596 | On a Cisco Catalyst switch, I need to find what port an end device is connected to. I have the IP address/host name. How do I quickly find the port? | The answer depends on whether the switch is a Layer 2 or a Layer 3 switch. That is to say, is the switch only switching and relaying traffic on to a different device for routing, or, is it doing the routing decisions itself via SVIs (switched virtual interfaces). On a layer 3 switch, the port can be found by using a few simple commands on the device. However on a layer 2 switch, you have to log into both the switch and whatever device is doing the routing to locate the port. In either case, the commands are the same, just run on two different boxes for the layer 2 switch. On a Layer 3 switch: Log into the switch and issue the following command (where ipaddress is the ip address of the host you are trying to locate: show ip arp *ipaddress* The output should look similar to below, and give you the mac-address of the device (I've highlighted the mac-address below in bold). LYKINS-1861#show ip arp 172.20.1.100
Protocol Address Age (min) Hardware Addr Type Interface
Internet 172.20.1.100 0 **28cf.da1d.1b05** ARPA Vlan10 Now issue one of the following commands (where mac-address is the hardware address from previous step). Depending on the Cisco platform, sometimes the command is listed in either form. show mac address-table address *mac-address*
show mac-address-table address *mac-address* The output should look similar to below, the port you are looking for should be listed as the Destination Port: LYKINS-1861#show mac-address-table address 28cf.da1d.1b05
Destination Address Address Type VLAN Destination Port
------------------- ------------ ---- --------------------
28cf.da1d.1b05 Dynamic 10 **FastEthernet0/1/1** On a Layer 2 switch: Find out what device is doing the routing for this switch (you may have to look at the network documentation). Sometimes it is a " Router on a Stick ", where the Layer 2 VLANs are being trunked up to the router for the Layer 3 decisions. Log into the routing device, and issue the following command (where ipaddress is the ip address of the host you are trying to locate: show ip arp *ipaddress* The output should look similar to below, and give you the mac-address of the device (listed below in bold). LYKINS-1861#show ip arp 172.20.1.100
Protocol Address Age (min) Hardware Addr Type Interface
Internet 172.20.1.100 0 **28cf.da1d.1b05** ARPA Vlan10 Now log into the Layer 2 switch On that device issue one of the following commands (where mac-address is the hardware address from previous step). Depending on the Cisco platform, sometimes the command is listed in either form. show mac address-table address *mac-address*
show mac-address-table address *mac-address* The output should look similar to below, the port you are looking for should be listed as the Destination Port: LYKINS-1861#show mac-address-table address 28cf.da1d.1b05
Destination Address Address Type VLAN Destination Port
------------------- ------------ ---- --------------------
28cf.da1d.1b05 Dynamic 10 **FastEthernet0/1/1** | {
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607 | I'm studying networking and one of the most basic things I've been told countless times is that computers can't communicate outside of their own subnet. On the other hand, by looking at some ADSL setups, I've seen that in case where a fixed IP address is assigned to the user's WAN interface, a /32 subnet mask is used for the WAN interface and the default gateway is of course outside of the subnet. So how would the host with /32 subnet communicate with outside network? Here's a sort of a diagram of what I have: The DSL modem is set up to act as a bridge so Router0 does authentication and sets up connection via PPPoE to the ISP. The Router0 gets an IP address on its WAN interface (Fa0/0 on the diagram) which is from a /32 subnet using IPCP. It only receives a single IP address on the WAN interface and IP aliasing isn't being used here. I understand what goes on from the Router0 to the LAN. What I don't understand is how does the Router0 communicate with ISP. | DSL tends to use PPPoE, which means the link is point-to-point. A /32 is perfectly valid here. In fact, no address at all is still valid -- one would need routable addresses beyond the PPP link, 'tho. In this case, it works because there's only one possible destination on the link. Every packet put on that link will be processed by the other end, and v.v. blue-gw#show int di1
Dialer1 is up, line protocol is up (spoofing)
Description: Bellsouth.net DSL
Internet address is 74.167.x.x/32
Routing:
Gateway of last resort is 72.157.24.5 to network 0.0.0.0
...
72.0.0.0/32 is subnetted, 1 subnets
C 72.157.24.5 is directly connected, Dialer1
74.0.0.0/32 is subnetted, 1 subnets
C 74.167.x.x is directly connected, Dialer1 | {
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640 | For investigating a problem in client to server communication, I need to capture packets for analysis. However it's not allowed to install a packet analyzer, such as Wireshark or tcpdump, on client or server. They client is connected to a Catalyst 3560 and the server to a Catalyst 3750 switch. Can I plugin my laptop to a switchport for capturing traffic with my laptop's packet analyzer, and how? | The client switchport or the server switchport can be monitored. A third switchport can be configured as a mirror port . This means that this mirror port will receive copies of all packets on the corresponding original port, while the original traffic won't be affected. For example, on the Catalyst 3560: Enter configuration mode: conf t Define the source and set the session number: monitor session 1 source interface fa 0/24 Here, the session number can be from 1 to 66, you could also specify a VLAN or an ethernet channel. Also, interface ranges such as fa 0/25 - 26 are possible, and interface list, such as fa 0/24,fa 0/26 , if you would like to monitor several clients at the same time. Also by repeating the command you can add ports, or remove using no . Mixing ports and VLANs is not possible in the same session, another restriction is that you cannot use a destination port as a source port. Define the destination port: monitor session 1 destination interface gi 0/1 You can use a normal port, but not a VLAN. Similarly to above, a destination port cannot be a source port: a port used here can either be a source or a destination port, and only of one session. Again, you can specify multiple ports like above. You may want to exit configiration mode and save the config. You may have a look at your defined session - here multiple ports, tried like above: #show monitor session 1
Session 1
---------
Type : Local Session
Source Ports :
Both : Fa0/24,Fa0/25-26
Destination Ports : Fa0/48,Gi0/1
Encapsulation : Native
Ingress : Disabled You can see an encapsulation here - optionally you can set it to replicate for replicating the source interface encapsulation method, such as by adding encapsulation replicate after the source interface. Furthermore, you can specify a direction ( tx , rx , both ), filter VLANs and more. The Ingress: Disabled line means that the switch will not accept any frames presented to it by your capture device on a destination port. For such finer details and for further restrictions and default settings have a look at the command reference of the IOS version of your switch. Once you configured source and destination port, you can capture the traffic using your laptop connected to the destination port, for example with Wireshark. The number of source sessions can be limited, for example the 3560 supports a maximum of 2. After the capturing, don't forget to remove this session configuration. | {
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644 | On a site-to-site VPN using a ASA 5520 and 5540, respectively, I noticed that from time to time traffic doesn't pass any more, sometimes just there's even missing traffic just for one specific traffic selection / ACL while other traffic over the same VPN is running. It happens even though there's a constant ping running. The reason might be that it runs over a satellite link which isn't perfectly stable. How can I reset the VPN to the working state, instead of reloading one of the ASAs? | The VPN can be reset by entering clear crypto ipsec sa peer <remote-peer-IP> on one side. The following traffic will cause the IPSEC tunnel to be reestablished. You can do it on your side, entering the remote IP. Or login to the remote site, but possibly you have to do it outside the VPN, so using a different interface, for example using the public IP instead of the IP to which you connect through the tunnel. There will be a short VPN outage while reestablishing the tunnel. After entering that command, ensure that the tunnel is up again, such as doing a ping through it. | {
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653 | On a large Cisco Catalyst switch stack, almost all switchports are patched. I need to identify the ports, which are not in use, for connecting further devices. Following switchports, cabling, patch fields and sockets to possible end devices is laborious and even then there could be temporarily used sockets. Looking at the activity of port LEDs is not reliable, since a user device can be shut off. What's the easiest way to detect all unused switchports via IOS commands? | I frequently use sh int | i (FastEthernet|0 packets input) or the same with GigabitEthernet, whatever kind of interfaces I want to check. sh int (which is show interfaces ) gives a huge list of ste status of all interfaces The pipe symbol | can be used for filtering, but also in search expressions | i (for include ) filters the output which matches the following search expressions I use (...|...) to match two conditions: the interface name and a status I like to see, we can use regular expressions here, like this "or" expression The output can look like: ...
FastEthernet1/0/31 is up, line protocol is up (connected)
95445640 packets input, 18990165053 bytes, 0 no buffer
FastEthernet1/0/32 is up, line protocol is up (connected)
FastEthernet1/0/33 is up, line protocol is up (connected)
FastEthernet1/0/34 is down, line protocol is down (notconnect)
0 packets input, 0 bytes, 0 no buffer
FastEthernet1/0/35 is down, line protocol is down (notconnect)
FastEthernet1/0/36 is up, line protocol is up (connected)
FastEthernet1/0/37 is down, line protocol is down (notconnect)
0 packets input, 0 bytes, 0 no buffer
... Now I can see my candidates, with actually 0 packets input over time, even if my expression matches numbers just ending with 0. I could make it more perfect, but being easy to remember is also a benefit. The interface names right before each 0 packets input lines are my candidates. Check each chosen interface if it's really unused by sh int <name> From time to time, it's good to clear the counters: clear counters [type number] It can be good practice, to leave unused switchports shutdown. So it's easy to identify them using sh ip int bri or the like. And you don't run into problems if you use a switchport which was definitly shut off before. | {
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732 | What's the basic use case(s) for VLANs? What are the basic design principles? I'm looking for something like a two paragraph executive summary style answer so I can determine if I need to learn about VLANs to implement them. | A VLAN (Virtual LAN) is a way of creating multiple virtual switches inside one physical switch. So for instance ports configured to use VLAN 10 act as if they're connected to the exact same switch. Ports in VLAN 20 can not directly talk to ports in VLAN 10. They must be routed between the two (or have a link that bridges the two VLANs). There are a lot of reasons to implement VLANs. Typically the least of these reasons is the size of the network. I'll bullet list a few reasons and then break each one open. Security Link Utilization Service Separation Service Isolation Subnet Size Security: Security isn't itself achieved by creating a VLAN; however, how you connect that VLAN to other subnets could allow you to filter/block access to that subnet. For instance if you have an office building that has 50 computers and 5 servers you could create a VLAN for the server and a VLAN for the computers. For computers to communicate with the servers you could use a firewall to route and filter that traffic. This would then allow you to apply IPS/IDS,ACLs,Etc. to the connection between the servers and computers. Link Utilization: (Edit)I can't believe I left this out the first time. Brain fart I guess. Link utilization is another big reason to use VLANs. Spanning tree by function builds a single path through your layer 2 network to prevent loops (Oh, my!). If you have multiple redundant links to your aggregating devices then some of these links will go unused. To get around this you can build multiple STP topology with different VLANs. This is accomplished with Cisco Proprietary PVST, RPVST, or standards based MST. This allows you to have multiple STP typologies you can play with to utilize your previously unused links. In example if I had 50 desktops I could place 25 of them in VLAN 10, and 25 of them in VLAN 20. I could then have VLAN 10 take the "left" side of the network and the remaining 25 in VLAN 20 would take the "right" side of the network. Service Separation: This one is pretty straight forward. If you have IP security cameras, IP Phones, and Desktops all connecting into the same switch it might be easier to separate these services out into their own subnet. This would also allow you to apply QOS markings to these services based on VLAN instead of some higher layer service (Ex: NBAR). You can also apply ACLs on the device performing L3 routing to prevent communication between VLANs that might not be desired. For instance I can prevent the desktops from accessing the phones/security cameras directly. Service Isolation: If you have a pair of TOR switches in a single rack that has a few VMWare hosts and a SAN you could create a iSCSI VLAN that remains unrouted. This would allow you to have an entirely isolated iSCSI network so that no other device could attempt to access the SAN or disrupt communication between the hosts and the SAN. This is simply one example of service isolation. Subnet Size: As stated before if a single site becomes too large you can break that site down into different VLANs which will reduce the number of hosts that see need to process each broadcast. There are certainly more ways VLANs are useful (I can think of several that I use specifically as an Internet Service Provider), but I feel these are the most common and should give you a good idea on how/why we use them. There are also Private VLANs that have specific use cases and are worth mentioning here. | {
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789 | Can someone explain with an example whats the difference between an access list and prefix list. | Here's the history of how they came into being (and why they are the way they are): In the very early days of the Internet, people started asking for packet filters (aka access lists). Cisco implemented simple access lists first (filtering on destination host addresses, augmented by wildcard masks), but of course they weren't good enough to block (for example) SMTP, so they created extended access lists, which can match on source and destination IP addresses (with wildcards bits on both - these bits allow you to match whole prefixes), protocols, port numbers ... So: access list = packet filter. Later (but still decades ago) people started running multiple routing protocols on the same box and wanted to redistribute information between them. Not a problem, but you wouldn't want ALL the information you have propagated into the other routing protocol - you need ROUTE FILTERS. As is usually the case, everything looks like a nail if you happen to have a hammer, and thus Cisco's engineers implemented route filters with the object they already had - access lists. At this point: access list = packet filter (and sometimes route filter) With the advent of classless routing (yeah, it's that long ago - does anyone still remember the days of Class A, Class B and Class C addresses), people wanted to redistribute prefixes of certain size between routing protocols. For example: advertise all /24s from OSPF into BGP, but not the /32s. Impossible to do with access lists. Time for a new kludge: let's use extended access list and let's pretend the source IP address in the packet filter represents network address (actually prefix address) and the destination IP address in the same line of the packet filter represents subnet mask. This far: access lists = packet filters. Simple access lists also serve as route filters (matching only on network addresses) and extended access lists serve as route filters matching addresses and subnet masks. Fortunately someone retained a shred of reason at that time and started wondering what exactly the brilliant minds that decided reusing extended ACLs for route filters makes sense were smoking when they got that brilliant idea. End result: Cisco IOS got prefix lists, which are (almost) identical in functionality to extended access lists acting as route filters, but displayed in a format that a regular human being has a chance of understanding. Today: use access lists for packet filters and prefix lists for route filters. You can still use access lists as route filters but don't do it . Makes sense? | {
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792 | Are there any significant differences between VRRP and HSRP? | Besides VRRP not being proprietary, there are a few minor differences between the protocols as well: With HSRP, each interface must have an IP address that is separate from the HSRP group address. VRRP lets you share the Master's interface IP address. On Cisco devices, VRRP is configured to preempt by default, whereas HSRP is not configured to preempt by default. On Cisco devices, HSRP sends hellos every 3 seconds and has a dead timer of 10 seconds. VRRP sends advertisements every 1 second and has a dead timer of roughly three times the advertisement interval. VRRP can be configured to learn the timer configuration from the Master. | {
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1,029 | You often hear the terms Subnet and VLAN used interchangeably. With the ubiquitous nature of IP these days, when are the two not considered roughly the same from a high-level, understanding that VLANs are L2 and Subnets are L3. In other words, are there any cases for having a VLAN without a Subnet, and still have IP (L3) communication? [Also ignoring that all networks are not subnets when considering classful networks which all are really just CIDR prefixes these days.] | If they are used interchangeably then they are used incorrectly. Subnet refers to particular IP network, such as 192.0.2.0/28 . VLAN refers to 802.1Q standard , in which you can essentially give each port unique MAC address table, effectively separating them from each other. VLAN may transport one or more subnet (but does not have to, it may be transporting something else than IP entirely).
Subnet may be configured for VLAN, but does not have to be, it could be without 802.1Q or over some completely different L2 technology than ethernet. | {
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1,160 | How is sFlow different from netFlow, and how is each supported by different vendors ? | NetFlow is a protocol for exporting aggregated IP flow totals. As such it is well suited to IP traffic accounting on Internet routers. With Netflow V9 (AKA IPFIX it can look into Layer 2 traffic as well) sFlow is a general purpose network traffic measurement system technology. sFlow is designed to be embedded in any network device and to provide continuous statistics on any protocol (L2, L3, L4, and up to L7), so that all traffic throughout a network can be accurately characterized and monitored. These statistics are essential for congestion control, troubleshooting, security surveillance, network planning etc. They can also be used for IP accounting purposes. Netflow mirrors all traffic, and places a load on the CPU when utilised. SFlow is a packet sampling technology where the switch captures every 100th packet (configurable) per interface and sends it off to the collector. sFlow is built into the ASIC, and places minimal load on the CPU. Netflow supported by Cisco, Juniper, Alcatel Lucent, Huawei, Enterasys, Nortel, VMWare sFlow supported by Alaxala, Alcatel Lucent, Allied Telesis, Arista Networks, Brocade, Cisco, Dell, D-Link, Enterasys, Extreme, Fortinet, Hewlett-Packard, Hitachi, Huawei, IBM, Juniper, LG-Ericsson, Mellanox, MRV, NEC, Netgear, Proxim Wireless, Quanta Computer, Vyatta, ZTE and ZyXEL ( see sFlow link ) | {
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1,190 | I am adding a new VLAN to an existing trunk port between two Cisco Catalyst switches (3750's). In the process of adding the new VLAN, it appears that I've removed the existing allowed VLANs on the trunk... How is this possible? Existing trunk port configuration: SW-LAB-1#show run int g1/0/49
Building configuration...
Current configuration : 255 bytes
!
interface GigabitEthernet1/0/49
description SW-LAB-2 G1/0/48
switchport trunk encapsulation dot1q
switchport trunk native vlan 10
switchport trunk allowed vlan 10,20
switchport mode trunk
switchport nonegotiate
ip dhcp snooping trust
end I used the following syntax to also allow VLAN 30: SW-LAB-1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
SW-LAB-1(config)#interface g1/0/49
SW-LAB-1(config-if)#switchport trunk allow vlan 30 However now, my running config on g1/0/49 is missing VLANs 10 and 20! <SNIP>
switchport trunk allowed vlan 30
</SNIP> What am I missing? | You need to use the following command to add your VLAN 30 to an existing Dot1Q trunk on a Cisco Catalyst switch: switchport trunk allowed vlan add 30 Otherwise IOS just thinks you're trying to overwrite the existing configuration and you are left with an accidentally deleted set of allowed VLANs. You could similarly use "remove" in place of "add" to remove only one VLAN. See the entire syntax below. (It is actually the same syntax in Cisco Nexus OS or IOS, FYI.) SW-FOO(config-if)#switchport trunk allowed vlan ?
WORD VLAN IDs of the allowed VLANs when this port is in trunking mode
add add VLANs to the current list
all all VLANs
except all VLANs except the following
none no VLANs
remove remove VLANs from the current list Another option is to put all of your allowed VLANs into the command, like so: switchport trunk allowed vlan 10,20,30 This option is more time consuming but also works. | {
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1,217 | I'd like to start exploring QoS, and lower level optimizations for things like broadcasts/multicasts within my home lab. I've looked around for ways to generate traffic to and from a box, but haven't found anything to really max out what a given port can handle to really see the effects of QoS etc. I'd love to be able to watch in real time via PRTG or some other monitoring tool - a maxed out line or a busy line(s) before implementing QoS and then be able to see the change in real time. What tools are availableto assist with these tasks? | You can use iperf2 or iperf3 to help generate some traffic. There are quite a few options included that will allow you to accomplish some nice traffic classification. You might also check out scapy - specifically a packet former utility. Allows you to define values on each field to get really granular with how traffic is being formed and sent. In my lab, I have two virtual machines at opposite ends of a physical network. I use both tools I mentioned to send traffic between the virtual machines, but that traffic goes through my lab topology of Cisco routers/switches/firewalls. This way I can have a reliable flow of traffic that I define ahead of time per the lab scenario. | {
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1,396 | In order of preference/priority, what factors do you consider in driving an upgrade (or downgrade) with Cisco IOS? If no compelling factors exist, how long would you allow a particular version of IOS to stay running? I've seen some switches with uptimes > 5 years. And when upgrading, how is the specific IOS release identified as the upgrade target? | In order of preference/priority, our company tends to upgrade based on these factors: Vulnerabilities, vulnerabilities, vulnerabilities! Bugs Attaining new features not currently available-- new cards/modules have a "first supported in" IOS version which could be higher than what you have running Migrating away from retired release trains Matching versions on more recently deployed and similar hardware A device that is very critical to the infrastructure may not be as aggressively upgraded as one that is less critical. Consideration is given to the role of the device, the redundancy surrounding it, and the impact of the upgrade itself by the downtime incurred or by the possibility of having config feature behavior changes or different defaults when going between major versions. This is the necessity question that also touches on soft costs such as the time and resources to accomplish the upgrades measured against the weight given to each of the factors such as vulnerabilities. Be sure to subscribe to multiple vulnerability announcement sites such as Cisco PSIRT (Product Security Incident Response Team) and the US Cert (Computer Emergency Readiness Team). A downgrade might be in order if: Organization has a policy to only run tested/QA'd versions and new equipment came with a more recent release. Org has a policy against running anything other than GD. Use Cisco's Output Interpreter of "show version" to look for obvious
issues/vulnerabities/bugs. Look for GD (General Deployment) releases and avoid DF (Deferred). Use ED (Early Deployment) only when it contains must-have features not available elsewhere. Avoid LD (Limited Deployment) when possible and use GD instead. There are certainly arguments for going to an ED or LD version, but the desire, of course, is to get to the most stable version that meets requirements. Use Cisco's Feature Navigator to help identify potentially different feature-sets (assuming you're licensed to use them). | {
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1,467 | If the CRC counter of an interface is high, normally it's a bad sign, but why? If the count is high, what does this mean technically? What can cause this counter to go up? On which layer in the OSI model will this counter react? | The counter is increasing because your frames are being corrupted. CRC is a polynomial function on the frame which returns a 4B number in Ethernet. It will catch all single bit errors and a good percentage of double bit errors. It is thus meant to ensure that the frame was not corrupted in transit. If your CRC error counter is increasing it means that when your hardware ran the polynomial function on the frame, the result was a 4B number which differed from the 4B number found on the frame itself. Ethernet frame CRC (FCS) is usually understood to be on OSI layer 2, many people claim it is layer 1 on Ethernet, but that is incorrect (only preamble, SFD and IFG are layer 1 on Ethernet). I recommend a book called Computer Networks - A systems approach on this and many other subjects. It discusses CRC in-depth around page 92 through 102. As Daniel pointed out, frames can get corrupted due to several reasons such as: duplex mismatch, faulty cabling and broken hardware. However, some level of CRC errors should be expected and the standard allows up-to 10 -12 bit-error-rate on Ethernet (1 bit out of 10 12 can flip) and it's acceptable according to the standard. In copper the signal travels by transferring state between electrons (electrons themselves are not traveling very much) and in fiber the signal travels by the photons reflecting off the walls of the fiber. There is a non-zero chance that the photon will simply change due to heat on the walls or the state of the electrons will flip itself. So even in perfect situations some errors will always happen. It should be known that a bit is not a single photon or single state change of an electron; today you need many photons or electron state changes to express a single bit, so a single incorrect 'state' will not yield an error as a bit is the average state of many of these. | {
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1,472 | Is it possible to write an arbitrary line of text to the log of a Cisco IOS 12.x device? I should like to be able to put in markers when fetching configs via TFTP and I would like to be able to have log lines á la May 30 14:14:00.000: %CONFIG-REMARK: Halfway through the script! Now on to SomethingThatMightFail!
May 30 14:14:05.000: %CONFIG-REMARK: SomethingThatMightFail didn't fail! Woo! Continuing! | You can use the send log command: switch#send log Halfway through the script! gives my on a Catalyst 3750 with IOS 12.2 May 31 16:36:18: %SYS-2-LOGMSG: Message from 1(name): Halfway through the script! and with IOS 15.0: May 31 16:38:08: %SYS-7-USERLOG_DEBUG: Message from tty1(user id: name): Halfway through the script! | {
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1,586 | So, I'm reading for a networking exam, and I'm just wondering if I have missed something basic. Is there a need for more ip addresses than MAC addresses, and how would a node with one network adapter be assigned many ip addresses in that case? | MAC addresses only need to be unique in a local broadcast domain, not globally, so re-use of MAC addresses in different networks usually isn't a problem. The internet isn't one global broadcast domain and thus needs to be divided into many blocks of addresses assigned to different ISP's and each ISP divides his blocks into smaller blocks for different customers/services. To allow each of these smaller blocks to contain many MAC addresses you need to have the IP-space much bigger than the MAC address space. | {
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1,976 | Why isn't it sensible to dedicate more than one TCP/IP port to http? Although admittedly naive, isn't it intuitive to think that server performance could somehow be increased? | Port 80 is a well-known port, which means it is well-known as the location you'll normally find HTTP servers. You can find it documented in the HTTP/1.1 RFC . Having a default is useful precisely because you don't have to type it into your web browser with the URI.
If you run an HTTP server (or in fact any service) on a non-standard port, you force the client to remember which arbitrary 16-bit number you chose and type it in. In addition to this unfriendliness, there is no performance benefit: a port is just one part of the (dst ip:port, src ip:port) 4-tuple which uniquely identifies a TCP connection. If two connections share a dst ip:port , that doesn't mean they share some system resource - they can reside in different threads, or different processes. Now, if you have logically different services which both happen to use HTTP, there is no problem with running them on different ports. It just makes the URI a little uglier. | {
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1,993 | I'm not too clear on subnetting rules and experienced an error when I tried to assign 148.26.1.176/28 to an interface on my Cisco router. Can someone please explain why it was not allowing me to assign this address to the interface? I receive an error saying: Bad mask /28 for address 148.26.1.176 Is it outside the permissible range? | If you are using /28 network mask then 148.26.1.176 is the network address and therefore is not an assignable IP address for this subnet. For subnet 148.26.1.176/28 the range of assignable IP address is 148.26.1.177 to 148.26.1.190, as 148.26.1.176 is the network address and 148.26.1.191 is the broadcast address | {
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2,009 | I'm having difficulty wrapping my head around how to set this up and the MPLS vendor is being no help so I figured I would ask here. I have a 2 node MPLS each site having internet access on the same circuit the MPLS rides in on. These circuits replace dedicated internet access at each site with an IPSEC tunnel between the sites. We want to leave our existing firewalls in place as they provide content filtering and VPN services. I am trying to configure a layer 3 switch (a cisco SG300-10P) at each site to set up this scenario. The relevant info (ip addresses changed to protect my idiocy) Site A Local Lan: 172.18.0.0/16 Existing Firewall (internal): 172.18.0.254 MPLS Gateway to Site B: 172.18.0.1 Internet IP Range 192.77.1.144/28 Carrier Gateway to internet 192.77.1.145 Items 3 and 5 are on a single peice of copper coming from an adtran netvana (Carrier equip I have no access) Site B Local Lan: 192.168.2.0/23 Existing Firewall (internal): 192.168.2.1 MPLS Gateway to Site A: 192.168.2.2 Internet IP Range 216.60.1.16/28 Carrier Gateway to internet 216.60.1.16 Items 3 and 5 are on a single peice of copper coming from an adtran 908e (Carrier equip I have no access) So given the above what I want to do at each site is set up these cisco switches so that: Port 1 = Carrier Connection
Port 2 = Interal Lan
Port 3 = Firewall Where the local lan is not exposed to the Internet IP range (ie if some yahoo sets their machine up on a provided internet ip with the carriers gateway it doesn't work) Or put differently from port 1 all traffic in the internet subnet can only exit on port 3 and from port 1 all traffic on the local lan subnet can only exit port 2. Every attempt I have made so far results in no access between the ports at all or basic dumb swith behavior (any host on any port can get across all of the IP ranges). First question here so please be kind. :) If you need more information I would be happy to provide it. | If you are using /28 network mask then 148.26.1.176 is the network address and therefore is not an assignable IP address for this subnet. For subnet 148.26.1.176/28 the range of assignable IP address is 148.26.1.177 to 148.26.1.190, as 148.26.1.176 is the network address and 148.26.1.191 is the broadcast address | {
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2,012 | Looking in Wireshark, I often see TCP Streams end with a RST, ACK packet instead of a RST packet. Anyone know why this is? An example of what I see: SYN
SYN, ACK
...data...
RST, ACK Wireshark is not picking up a RST packet prior to the RST, ACK packet. | A RST/ACK is not an acknowledgement of a RST, same as a SYN/ACK is not exactly an acknowledgment of a SYN. TCP establishment actually is a four-way process: Initiating host sends a SYN to the receiving host, which sends an ACK for that SYN. Receiving host sends a SYN to the initiating host, which sends an ACK back. This establishes stateful communication. SYN -->
<-- ACK
<-- SYN
ACK --> To make this more efficient, the receiving host can ACK the SYN, and send its own SYN in the same packet, creating the three-way process we are used to seeing. SYN -->
<-- SYN/ACK
ACK --> In the case of a RST/ACK, The device is acknowledging whatever data was sent in the previous packet(s) in the sequence with an ACK and then notifying the sender that the connection has closed with the RST. The device is simply combining the two packets into one, just like a SYN/ACK. A RST/ACK is usually not a normal response in closing a TCP session, but it's not necessarily indicative of a problem either. | {
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2,024 | I am new to network Engineering. I find it is hard to distinguish and understand different switchport settings. Why can I have a switchport set to access, auto, or dynamic? What are they used for? Are those functions only used for a host to switch connection? What is "switchport nonnegotiate" used for? | Welcome to the field of network engineering! DTP stands for Dynamic Trunking Protocol and is crucial to the commands below. It is also Cisco proprietary. switchport mode access - Always forces that port to be an access port with no VLAN tagging allowed EXCEPT for the voice vlan. DTP is not used and a trunk will never be formed. switchport nonegotiate - turns off DTP and forces the interface into a trunk. switchport mode dynamic desirable - pro-active DTP negotiation will begin and if the other-side is set to trunk , desirable , or auto . The interface will become a trunk. Otherwise the port will become an access port. switchport mode dynamic auto - allows the port to negotiate DTP if the other side is set to trunk or desirable . Otherwise it will become an access port. switchport mode trunk - This interface will always be a trunk no matter what happens on the other side. It will also use DTP to negotiate a neighbouring interface that is set to dynamic desirable or dynamic auto into a trunk. In the real world - I have never seen *dynamic auto *or dynamic desirable as generally network engineers try and make layer 2 related items (such as switchport settings) stable and static. There are also security risks associated with this. An access role port is usually used for an single host or device.
You must also specify which VLAN you would like it to be associated with, otherwise it will default to VLAN 1 in the Cisco world.
eg) interface gig0/1 switchport mode access switchport access vlan 10 Also, if you have a VLAN for voip traffic. You can also set the voice vlan as required by adding switchport voice vlan 20 A trunk port is generally only used when you want to interconnect two switches together in order to pass multiple VLANs between the two switches.
In this example, the switches will use Dot1Q tagging and allow vlans 10, 20 & 30 to be passed between the two switches. Vlan 10 however, will be passed without tagging since it is set as the native vlan.
eg) Switch1# interface gig0/1 switchport encapsulation dot1q switchport mode trunk switchport trunk native vlan 10 switchport trunk allowed vlan 10,20,30 Switch2# interface gig0/1 switchport encapsulation dot1q switchport mode trunk switchport trunk native vlan 10 switchport trunk allowed vlan 10,20,30 Take a look at Implement trunk and trunk protocols for more examples and to learn more about ISL or dot1q tagging along with some more command and debug information. | {
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2,283 | Consider a list of IP addresses as provided by the X-Forwarded-For HTTP header : 10.0.0.142 , 192.168.0.10 , 212.43.234.12 , 54.23.66.43 I would like to know which is the first publicly-accessible address in that list. I can look over them easily enough, but how can I tell which are publicly-accessible? It seems to me (my untrained eye) that 10.0.0.142 is a workstation, 192.168.0.10 is an internal proxy, and 212.43.234.12 is a publicly-accessible address being forwarded through the proxy at 54.23.66.43 . Is there any way to calculate this in code? My first intuition is that addresses that start with 10. or 192. are not publicly accessible, but http://simplesniff.com reveals my home IP address to be 192.117.111.61 . Is there a formula for determining which addresses are public and which are reserved private? Note that even trying to ping the server in question might not help as some servers won't respond to ping, and also there might be an address on my local network which also matched the internal address. | RFC 1918 defines private IP address ranges. Have a look here. From that document: Private Address Space The Internet Assigned Numbers Authority (IANA) has reserved the
following three blocks of the IP address space for private internets: 10.0.0.0 - 10.255.255.255 (10/8 prefix) 172.16.0.0 - 172.31.255.255 (172.16/12 prefix) 192.168.0.0 - 192.168.255.255 (192.168/16 prefix) | {
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3,129 | Lately I have been checking datasheets of several switch models from diferent vendors. For a given switch, vendors publish a couple of figures that I think are a measure of the capacity/performance of the switch: One value is always measured in packets per second The other one is always measured in bits per second Despite different vendors use different names for the figures, seems the meaning is always the same. I would like to understand three things: What is the exact meaning of each figure? What is the difference between them? When should I focus on each value for switch assessment? | I just want to briefly mention the reality of marketing math when you're considering vendor data sheets. It is very common for vendors to double-count bps or pps capacity when you have full-duplex links. For instance, Cisco's Catalyst 6500 has a Supervisor 720. 720 is used because it is marketed as having 720Gbps of fabric capacity. But... if you ask how Cisco calculates 720Gbps, the answer is: 80Gbps of fabric per slot times 9 slots in a chassis The issue here is their fabric is only a 40Gbps full-duplex fabric... However, Cisco counts both ingress and egress in the 720G number, even though it doesn't really make sense to count like that. The take-away is you sometimes need to be careful and inspect how you can apply the numbers in vendor literature to reality. Almost every vendor twists marketing numbers like this, and I only pick the Cat6500 because I'm very familiar with the platform. This is not a condemnation of Cisco or the Cat6500 (which I actually have quite a passion for). What is the exact meaning of each figure? What is the difference between them? bps Number of bits of data per second that can be processed without dropping data. bps is almost always measured using 1500 byte (or potentially larger) ethernet payloads. bps is frequently used when measuring the capacity of components which interconnect multiple linecards or ports within a chassis (like a switch fabric). Occasionally, a central processing engine might have a bps limitation... pps Number of packets of data per second that can be processed before dropping data; pps is always measured using the smallest packet sizes possible. pps is frequently used when measuring components that look inside a packet header (for an IP address, mac-address, DSCP value, etc...). For example, the capacity of route and switch processors are measured in pps. When should I focus on each value for switch assessment? There is a time and place for this kind of analysis, but most people only use a tiny fraction of their switch pps / bps capacity, unless it's a top of rack switch in a busy data center, or a core switch for a mid to large service provider POP. Even so, vendor sales staff might not be interested in highlighting the product limitations, or may not understand the limits well themselves. Also, the packet-per-second numbers often change depending on the features, or combination of features that you turn on... there really is no substitute for coming up with a few good test cases, and testing the performance of the box with the combination of features you think you realistically need. Due to variances and the games people can play with numbers on data sheets, the most important thing you can ask the vendor is " show me how you calculated the bps and pps numbers for this component ". That said, hardware and software features are as important, or more important to consider than drag-race bps / pps numbers... I'm including a small sample of items you might want to look at... this is very subjective... On forwarding engines (normally measured in pps) Add up the bandwidth of an average chassis port count, and find the average packet size (at the advertised non-drop rate) with features on and then with off (compare how these numbers may change) Aggregate IPv4 / IPv6 / MPLS pps performance (these numbers may change, depending on the platform, or combinations of features that you use) ACL rule limitations (on number of ACEs, header fields you can filter on, counters, etc...) Total number of prefixes / mac addresses supported in HW and in DRAM SNMP MIBs supported QoS modes and features supported, as well as how easily you can integrate these QoS features into the rest of your network. Route processor failover times Availability and reliability of In service software upgrades Does the OS have modular software components Are Vlans locally significant to an interface, or does the box have global vlan utilization fabric / linecard fabric connections / linecard ASICs (normally measured in bps) Average cost per 1GE or 10GE port Port count and linecard oversubscription ratios Linecard and port buffer sizes Whether the switch supports backpressure to ingress linecards, if the egress fabric port is congested Ingress vs Egress multicast replication | {
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3,329 | If my computer has an IP address,why does it need a MAC address? | Without going into OSI model, TCP layer, etc.: Back in time, networks were created: some computers would communicate with each other to share something. TO do that, they need to know who was talking and who was being talked to. So, instead of giving each computer a name, we gave them an ID. This ID is called MAC address, is should uniquely identify each computer. (ok, identify each network card, but back that time, you could think of one MAC address for each computer). There wasn't a unique specification on how computers would talk to each other: many protocols appeared: TCP/IP, IPX/SPX, and so on. Each protocol would specify things as they thought were ok. For example, IPX/SPX would address each computer using the MAC address and some more information. But the TCP/IP protocol was designed a little bit different: they decided that having an virtual address, made of 4 bytes (0.0.0.0 to 255.255.255.255) was enough, and was even easier to manage: it doesn't matter if your network cards all have a similar MAC address or not; we'll group our computer so that all TCP/IP address that began with 10.0.x.x. are part of the engineering group, and those of 10.1.x.x. are the printers, and... So, if a TCP/IP address needs to communicate with another, is just uses the TCP/IP address. But the network devices need to know to which network card that message is going, so they, somehow, translate the TCP/IP address with to the MAC address. Why not simply eliminate the MAC and instead use just TCP/IP ? some reasons: easy to group TCP/IP addresses, all devices are built to take care of the MAC address, in that low-level requirement, and would need to be changed. despite being the vast majority (I think :-P ), some other protocols are still in use and they rely on the MAC address. | {
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3,482 | The Tag Protocol Identifier is set to 16 bits.
In the CCNA certification it is said that it's not possible to have more than 4096 VLANs.
4096 in binary is 1000000000000000.
Since 16 bits are allocated anyway, the limit could be 65535(1111111111111111)... Why is that limit set to 4096? | Only 12 bits are used for VLANs in 802.1q, so you can only use VLANs from 0-4095 (=4096* different VLANs). *actually 2 less, 0 and 4095 are reserved http://en.wikipedia.org/wiki/IEEE_802.1Q#Frame_format PS: 4096(DEC) is 1000000000000(BIN)
4095(DEC) is 111111111111(BIN) | {
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3,697 | What does the "/16" means in here : "192.168.0.0/16" , for example. | A simple explanation: The /<number> is how a computer can quickly calculate what is part of its network and what is not. It represents the bit length of the subnet mask, as indicated above. The subnet mask is like masking when painting. You place a mask over what you DO NOT want to paint on. The subnet mask is a way to calculate the network portion of the address space and the host address space. The network address space is assigned to you, the host address space you define which device receives what address in the host space. A computer performs binary math of ANDing the IP address and the network mask. IP Address 10.10.15.10/16 Step 1)
Translate the IP address 4 octets into binary: 00001010.00001010.00001111.00001010 Step 2)
Translate the Subnet mask 4 octets into binary, which is easy using CIDR : 11111111.11111111.00000000.00000000 Step 3)
Perform the ANDing operation on the two addresses. This will give you the Network Address for the subnet. ANDing rules are as follows: 1 AND 1 = 1 0 AND 1 = 0 0 AND 0 = 0 1 AND 0 = 0 00001010.00001010.00001111.00001010
AND 11111111.11111111.00000000.00000000
———————————————————————————————————
00001010.00001010.00000000.00000000 Step 4)
Convert it back to decimal: 10.10.0.0 So now a computer knows that any address from 10.10.0.0 to 10.10.255.255 is part of its network and any other address is not. It's like a binary network gang thing, you are in or you are not. | {
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3,909 | Can anyone explain why we need iBGP for the routes when we have the IGP protocols (OSPF, RIP) for internal communication within the AS? I have read a lot of articles and books, but I could not find the answer. | Can anyone explain me what is the need of IBGP communication for the routes, when we have the IGP protocols (OSPF, RIP) for internal communication? Scalability 1 : Imagine that you're receiving 500,000 EBGP routes in more than one location 2 , and you need to influence the per route exit point in your AS. BGP can handle many more routes than IGP protocols. Thus, iBGP is required unless you're willing to redistribute all the routes you've learned via eBGP Enforce boundaries of trust / control: BGP has more ways to filter peers than IGPs (for controlling what you advertise and receive). Flexible data structures (somewhat related to the previous bullet): BGP communities , BGP Extended communities , local-pref , etc... these make BGP an attractive way to implement custom routing policies within your own autonomous system (by using iBGP). As with everything there are trade offs; the scalability, control, and flexibility you get from iBGP means that it's a slower converging protocol than IGPs (in general). End Notes: 1 Scalability : You use BGP because you don't want to carry your entire internet routing table in your IGP (i.e. in my case, OSPF)... OSPF was not designed to handle many thousands of routes in internet BGP tables... if you try to use OSPF for this purpose, it will break your network. Using the example of OSPF, the LSA processing / flooding requirements from 500,000 routes uses too many resources in your routers. Name any other IGP (EIGRP, RIPv1/2, IS-IS, IGRP) and the same story is true. There have been some notorious instances where a Tier-1 ISP accidentally redistributed their BGP table into their IGP (even when the internet table was a small fraction of its current size) and it caused major outages. Countermeasures have now been implemented in IGP protocols ( like this one for OSPF in IOS ) to prevent redistribution from BGP into OSPF from causing a major outage. 2 iBGP routing example : To understand why you might want iBGP, consider this routing entry to 4.2.2.2... R2>sh ip bgp 4.2.2.2
BGP routing table entry for 4.0.0.0/9, version 3146
Paths: (32 available, best #7, table Default-IP-Routing-Table)
... <!-- extra BGP RIB entries deleted -->
7660 2516 3356, (aggregated by 3356 4.69.130.4)
203.181.248.168 from 203.181.248.168 (203.181.248.168)
Origin IGP, localpref 100, valid, internal, atomic-aggregate
Community: 2516:1030
3356, (aggregated by 3356 4.69.130.6)
4.69.184.193 from 4.69.184.193 (4.69.184.193)
Origin IGP, metric 0, localpref 100, valid, internal, atomic-aggregate, best
Community: 3356:0 3356:3 3356:100 3356:123 3356:575 3356:2012
... <!-- extra BGP RIB entries deleted --> There are 32 paths to consider... In this case, BGP chose to go to 4.0.0.0/9 via 4.69.184.193 (notice the best under the RIB entry). In this case, BGP chose this because this route has the shortest AS Path list. However, not all routes will be preferred via AS3356 (attached to R1). Some may be preferred out R3 (via AS7660). iBGP gives you the ability to know (at R2) which way to go to take the shortest BGP path. BGP route to 4.0.0.0/9 via
NH: 4.69.184.193 [Path: 3356]
-------->
eBGP w/ AS3356 }{ iBGP inside AS64000 }{ eBGP w/ AS7660
S1/0 S1/2 S2/1 S2/3 S3/2 S3/0
Peered w/ AS3356 +------+ +------+ +------+ Peered w/ AS7660
4.69.184.193 <------| R1 |---------| R2 |--------| R3 |-----> 203.181.248.168
+------+ +------+ +------+
| S2/0
|
^
^
| Ingress packet to 4.2.2.2
| R1, R2 and R3 are fully-iBGP meshed. When iBGP advertises a route, the next-hop remains unchanged . This means I need to carry the subnet for 4.69.184.193 in OSPF... R2>sh ip route 4.69.184.193
Routing entry for 4.69.184.192/30
Known via "ospf 100", distance 110, metric 65536, type intra area
Last update from 192.0.2.109 on GigabitEthernet3/1, 1w0d ago
Routing Descriptor Blocks:
* 192.0.2.109, from 192.0.2.3, 1w0d ago, via Serial2/1
Route metric is 65536, traffic share count is 1
R2> Thus when a packet for 4.2.2.2 arrives at R2, R2 sends it out Serial2/1 because that's where iBGP tells us the next-hop is. | {
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