Using Paramiko with SOCKS proxy

Question

I an trying to use Paramiko with SOCKS proxy (SecureCRT or PuTTY configured as SOCKS proxy). I am using the below code

import paramiko,socks

host, port = '127.0.0.1', 1080

# Set up your proxy information for this socket
sock=socks.socksocket()
sock.set_proxy(
    proxy_type=socks.SOCKS4,
    addr=host,
    port=port,
)

# Connect the socket
sock.connect((host, port))

# Create your Paramiko Transport
transport = paramiko.Transport(sock)
transport.connect(
    username='username',     #<------not sure if it is needed, the socks proxy needs no username/password
    password='secret',
)
client = paramiko.client.SSHClient.connect('remotedevice', username='usernameonremotedevice',sock=sock)
stdin, stdout, stderr=client.exec_command("ls -la")
# Do stuff

# Clean up
client.close()
transport.close()

The above approach seems to confuse Paramiko since it is using 127.0.0.1 for both. My issue originated in the Paramiko libraries used by Exscript so I wanted to simplify to see if this would work ....

This is the log that SecureCRT shows with each attempt

[LOCAL] : Starting port forward from 127.0.0.1 on local 127.0.0.1:1080 to remote 127.0.0.1:1080.  
[LOCAL] : Could not start port forwarding from local service 127.0.0.1:3106 to 127.0.0.1:1080.  Reason: The channel could not be opened because the connection failed.  Server error details:     Connection refused  

The script fails like below:

Traceback (most recent call last):
  File "C:\Users\Username\Documents\Eclipse\ESNetworkDiscovery\ParamikoProxyTest.py", line 24, in <module>
    sock.connect((host, port))
  File "C:\Utils\WPy2.7-32\python-2.7.13\lib\site-packages\socks.py", line 96, in wrapper
    return function(*args, **kwargs)
  File "C:\Utils\WPy2.7-32\python-2.7.13\lib\site-packages\socks.py", line 813, in connect
    negotiate(self, dest_addr, dest_port)
  File "C:\Utils\WPy2.7-32\python-2.7.13\lib\site-packages\socks.py", line 667, in _negotiate_SOCKS4
    raise SOCKS4Error("{0:#04x}: {1}".format(status, error))
socks.SOCKS4Error: 0x5b: Request rejected or failed

Answer 1

The answer by @pynexj is correct, but having a full working example is always nice:

import socks
import paramiko

sock=socks.socksocket()
sock.set_proxy(
    proxy_type=socks.SOCKS5,
    addr="proxy.host.name.example",
    port=1080,
    username="blubbs",
    password="blabbs"
)
sock.connect(('ssh.host.name.example', 22))

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy()) # see SO comments
ssh.connect('ignored without host key verification', username='caesar', sock=sock)
print((ssh.exec_command('ls')[1]).read().decode())
ssh.close()

(Would be nice to know if sock has to be closed separately…)

Side note: Make sure to not use password authentication together with AutoAddPolicy. Preferrably, don't use password authentication at all. (See comments.)

Answer 2

sock.connect((host, port)) should use the SSH server's hostname (the same host you use for SSHClient.connect()) and port (default 22).