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request_port_forward is not reenterant #1710

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pyhedgehog opened this issue Jun 24, 2020 · 4 comments · May be fixed by #2381
Open

request_port_forward is not reenterant #1710

pyhedgehog opened this issue Jun 24, 2020 · 4 comments · May be fixed by #2381
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Bug Needs investigation

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@pyhedgehog
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Let's pretend we've configured everything to allow loopback connection without password...

import paramiko, socket
client = paramiko.SSHClient()
client.load_system_host_keys()
client.connect('localhost')
def handler1(chan, source, target):
    chan.send('test1')
    chan.close()
def handler2(chan, source, target):
    chan.send('test2')
    chan.close()
client.get_transport().request_port_forward('127.0.0.1', 30001, handler1)
s = socket.create_connection(('127.0.0.1', 30001))
print(s.recv(10).decode('latin1'))
s.close()
client.get_transport().request_port_forward('127.0.0.1', 30002, handler2)
s = socket.create_connection(('127.0.0.1', 30002))
print(s.recv(10).decode('latin1'))
s.close()
s = socket.create_connection(('127.0.0.1', 30001))
print(s.recv(10).decode('latin1'))
s.close()

Real output:

test1
test2
test2

Expected output:

test1
test2
test1
@pyhedgehog
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It's still here.

@gns24
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gns24 commented Feb 22, 2022

The issue is simpler than that - multiple port forwards just don't work.

import paramiko, socket
client = paramiko.SSHClient()
client.load_system_host_keys()
client.connect('localhost')

def handler1(chan, source, target):
    chan.send('test1')
    chan.close()

def handler2(chan, source, target):
    chan.send('test2')
    chan.close()

client.get_transport().request_port_forward('127.0.0.1', 30001, handler1)
client.get_transport().request_port_forward('127.0.0.1', 30002, handler2)

s = socket.create_connection(('127.0.0.1', 30001))
print(s.recv(10).decode())
s.close()

s = socket.create_connection(('127.0.0.1', 30002))
print(s.recv(10).decode())
s.close()

gives

test2
test2

@SiriusXT
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SiriusXT commented Feb 9, 2023

I have the same problem

@pyhedgehog
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pyhedgehog commented Apr 5, 2024 •
edited

In 3.4.0 it's still exists.
Cause of problem is following line:

paramiko/paramiko/transport.py

Line 1154 in 51eb55d

self._tcp_handler = handler

This overrides handler for every new forwarded port. We need dictionary that will map (listening) (address, port) to handler.
Obviously in cancel_port_forward() we should delete only one item of dictionary:
https://github.com/paramiko/paramiko/blob/main/paramiko/transport.py#L1168

@pyhedgehog pyhedgehog linked a pull request Apr 9, 2024 that will close this issue
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Fix request_port_forward to be reenterant pyhedgehog/paramiko
4 participants
@gns24 @pyhedgehog @bskinn @SiriusXT