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"""Sample script showing how to do local port forwarding over paramiko.
This script connects to the requested SSH server and sets up local port
forwarding (the openssh -L option) from a local port through a tunneled
connection to a destination reachable from the SSH server machine.
"""
#
# This file is adapted from a paramiko demo, and thus licensed under LGPL 2.1.
# Original Copyright (C) 2003-2007 Robey Pointer <[email protected]>
# Edits Copyright (C) 2010 The IPython Team
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02111-1301 USA.
import logging
import select
import socketserver
import typing as t
logger = logging.getLogger("ssh")
class ForwardServer(socketserver.ThreadingTCPServer):
"""A server to use for ssh forwarding."""
daemon_threads = True
allow_reuse_address = True
class Handler(socketserver.BaseRequestHandler):
"""A handle for server requests."""
@t.no_type_check
def handle(self):
"""Handle a request."""
try:
chan = self.ssh_transport.open_channel(
"direct-tcpip",
(self.chain_host, self.chain_port),
self.request.getpeername(),
)
except Exception as e:
logger.debug(
"Incoming request to %s:%d failed: %s" % (self.chain_host, self.chain_port, repr(e))
)
return
if chan is None:
logger.debug(
"Incoming request to %s:%d was rejected by the SSH server."
% (self.chain_host, self.chain_port)
)
return
logger.debug(
"Connected! Tunnel open {!r} -> {!r} -> {!r}".format(
self.request.getpeername(),
chan.getpeername(),
(self.chain_host, self.chain_port),
)
)
while True:
r, w, x = select.select([self.request, chan], [], [])
if self.request in r:
data = self.request.recv(1024)
if len(data) == 0:
break
chan.send(data)
if chan in r:
data = chan.recv(1024)
if len(data) == 0:
break
self.request.send(data)
chan.close()
self.request.close()
logger.debug("Tunnel closed ")
def forward_tunnel(local_port: int, remote_host: str, remote_port: int, transport: t.Any) -> None:
"""Forward an ssh tunnel."""
# this is a little convoluted, but lets me configure things for the Handler
# object. (SocketServer doesn't give Handlers any way to access the outer
# server normally.)
class SubHander(Handler):
chain_host = remote_host
chain_port = remote_port
ssh_transport = transport
ForwardServer(("127.0.0.1", local_port), SubHander).serve_forever()
__all__ = ["forward_tunnel"]
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