paramiko.Proxycommand fails to setup socket

Question

I am trying to connect via SSH to a computer tunneling through another computer using paramiko in Python, but I am having some strange issues.

My config file in /.ssh/config looks like this:

Host remoteA
HostName 169.254.1.1
User root
IdentityFile ~/.ssh/id_dss.openssh.remoteA
ForwardX11 no
StrictHostKeyChecking no
ForwardAgent yes
UserKnownHostsFile /dev/null
Host remoteB
User root
IdentityFile ~/.ssh/id_dss.openssh.remoteB
ForwardX11 no
StrictHostKeyChecking no
UserKnownHostsFile /dev/null
ProxyCommand ssh -W 169.254.1.2:22 remoteA

And my python code like this:

from paramiko import SSHClient,SSHConfig,SSHException
import getpass
import paramiko
def getSSHConnection(hostName):
     config = SSHConfig()
     user = getpass.getuser()
     config.parse(open('C:/Users/' + user +'/.ssh/config')) 
     host=config.lookup(hostName)
     # setup SSH client
     client = SSHClient()
     client.load_system_host_keys()
     client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
     #Check for proxy settings
     try:
        print host ['proxycommand']
        proxy = paramiko.ProxyCommand(host['proxycommand'])
    except:
        proxy = None
    #Setup the SSH connection
    try:
        if (proxy is None):
            client.connect(host['hostname'],22,username=host['user'],key_filename=host['identityfile'])
        else:
            client.connect(host['hostname'],22,username=host['user'], key_filename=host['identityfile'],sock=proxy)
    except SSHException,ex:
        print ex
    return client
ssh_client = getSSHConnection('remoteA')
# run a command
print "\nRun a command"
cmd = 'ps aux'
stdin,stdout,stderr = ssh_client.exec_command(cmd)
print stdout.read()
ssh_client = getSSHConnection('remoteB')
# run a command
print "\nRun a command"
cmd = 'ps aux'
stdin,stdout,stderr = ssh_client.exec_command(cmd)
print stdout.read()

First when connecting to remoteA it works perfectly,but then when connecting to remoteB it crashes in the step: proxy = paramiko.ProxyCommand(host['proxycommand']).

File "C:\Python27\lib\site-packages\paramiko\client.py",line 291,in connect
    for (family,socktype,proto,canonname,sockaddr) in socket.getaddrinfo(hostname,port,        socket.AF_UNSPEC,socket.SOCK_STREAM):
socket.gaierror: [Errno 11004] getaddrinfo failed

Within Cygwin,I am able to connect using the command ssh remoteB so I know the config file should be ok. If it makes any difference,I am running this on Windows 7.

Answer 1

I think you can stick to your first solution. Just you need to change your proxy command and make sure your jump host has got nc installed

I use a proxy command like this

proxy = paramiko.ProxyCommand("ssh -o StrictHostKeyChecking=no jumphostIP nc targethostIP 22")

I found this WiKi very useful http://en.wikibooks.org/wiki/OpenSSH/Cookbook/Proxies_and_Jump_Hosts Just use actual values instead of %h and %p as I have done.

Answer 2

So instead of using ProxyCommand I used port forwarding to solve my issue.

def getForwardedSSHPort(self, tunnnelHostName):
    forwarderClient = self.getSSHConnection(tunnnelHostName, None)
    transport = forwarderClient.get_transport()
    dest_addr = ('169.254.1.2', 22)
    local_addr = ('127.0.0.1', 10022)
    channel = transport.open_channel('direct-tcpip', dest_addr, local_addr)

    remoteClient = self.getSSHConnection( tunnnelHostName, channel)