Paramiko.ssh_exception.ProxyCommandFailure: "Broken Pipe")

Question

I am trying to ssh a tunnel from a PC -> server1 ---> server2 ----> switch1 This is possible through a regular terminal with a simple one: ssh switch1 it refers to my ssh_config, which reads:

 Host server1
  user bill
  Hostname server1
  ForwardAgent yes
  IdentityFile ~/.ssh/id_rsa
  ProxyCommand none

 Host server2
  user bill
  Hostname server2
  IdentityFile ~/.ssh/id_rsa
  ProxyCommand ssh server1 /usr/bin/nc %h %p

 Host switch1
  user bill
  Hostname %h.omniture.com
  ProxyCommand ssh server2 /usr/bin/nc %h %p

Not a problem from a regular terminal. But trying to create a python script for this turned out to be a daunting task.

The script looks like this:

 import paramiko
 import subprocess
 import getpass
 import os


 def ssh_command(ip, user, passwd, command):
     client = paramiko.SSHClient()
     client.load_host_keys('/Users/bill/.ssh/known_hosts')
     client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
     config = paramiko.SSHConfig()
     if os.path.exists('/etc/ssh/ssh_config'):
         config.parse(open('/etc/ssh/ssh_config'))
     if os.path.exists(os.path.expanduser('~/.ssh/config')):
         config.parse(open(os.path.expanduser('~/.ssh/config')))

     host = config.lookup(ip)
     if 'proxycommand' in host:
                 proxy = paramiko.ProxyCommand(
                 subprocess.check_output(
                 [os.environ['SHELL'], '-c', 'echo %s' %
                 host['proxycommand']]
                 ).strip()
             )
     else:
         proxy = None

     client.connect(host['hostname'], username='bill',
     password=getpass.getpass(), sock=proxy)
     ssh_session = client.get_transport().open_session()
     if ssh_session.active:
         ssh_session.exec_command(command)
         print ssh_session.recv(1024)
     return
 ssh_command('sw-a-102.sin2', 'bill', getpass.getpass(), 'show ver')

The error I am getting is:

No handlers could be found for logger "paramiko.transport"
Traceback (most recent call last):
  File "/Users/bill/git/tools/python/dns-check/proxy-test.py", line 34, in <module>
    ssh_command('switch1', 'bill', getpass.getpass(), 'show ver')
  File "/Users/bill/git/tools/python/dns-check/proxy-test.py", line 28, in ssh_command
    client.connect(host['hostname'], username='bill', password=getpass.getpass(), sock=proxy)
  File "/Library/Python/2.7/site-packages/paramiko/client.py", line 265, in connect
    t.start_client()
  File "/Library/Python/2.7/site-packages/paramiko/transport.py", line 406, in start_client
    raise e
paramiko.ssh_exception.ProxyCommandFailure: ('ssh server2 /usr/bin/nc switch1 22', 'Broken pipe')

If I can get this to work with paramiko, it would be great if someone knows a better way, that is good too. Thank you for your time.

Answer 1

, Paramiko, ProxyCommand .

paramiko proxy - , .

OTOH, SSH .

import paramiko

# Make clients
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.MissingHostKeyPolicy())
server2_client = paramiko.SSHClient()
server2_client.set_missing_host_key_policy(paramiko.MissingHostKeyPolicy())
switch1_client = paramiko.SSHClient()
switch1_client.set_missing_host_key_policy(paramiko.MissingHostKeyPolicy())

# Connect to server1 normally
client.connect('server1')

# Make channel server1 -> server2
server2_chan = client.get_transport().open_channel('direct-tcpip', ('<server2 ip>', 22,), ('127.0.0.1', 0))

# Connect to server2 via server1 channel
server2_client.connect('<server2 ip>', sock=server1_chan)

# Make channel server2 -> switch1
switch1_chan = server2_client.get_transport().open_channel('direct-tcpip', ('<switch1 ip>', 22,), ('127.0.0.1', 0))

# Finally connect to switch1 via server2 channel
switch1_client.connect('switch1', sock=server2_chan)
switch1_client.exec_command(<command>)

IP-.

. SSH- paramiko SSH-.