Paramiko ssh_config parameters

Question

I'm using python with paramiko (wrapped in pysftp) and there appears to be an issue where it will hang for a long time if it cannot authenticate during ssh. I can't figure out a way to set a timeout for the connection and I'm cycling through many machines, so a single machine that is pingable, but not ssh'able (can't reach via cmdline ssh either) is hanging everything. Using this:

ssh -o ServerAliveInterval=1 -o ServerAliveCountMax=1 <host>

I can at least get it to error out after 1 second without waiting for a long time for the authentication in paramiko to die out and raise an exception. However, I can't figure out how to pass these ssh_config options to paramiko (or better yet to apply a timeout to the connect). I tried using the SSHConfig module and that reads in a config file, but it doesn't seem to apply the data anywhere, seems more used for host aliases.

Any help would be appreciated, been searching around for information/help for many hours.

Answer 1

Establish the initial connection using SSHClient.connect() with a specified socket timeout, then create a SFTPClient using its transport.

Successful connection

>>> import paramiko
>>> client = paramiko.SSHClient()
>>> client.load_system_host_keys()
>>> client.connect(hostname='localhost', port=22, username='user', password='****', timeout=5.0)
>>> sftp = paramiko.SFTPClient.from_transport(client.get_transport())
>>> dirlist = sftp.listdir('.')

Timed out connection

>>> import paramiko
>>> client = paramiko.SSHClient()
>>> client.load_system_host_keys()
>>> client.connect(hostname='slowhost', username='user', password='****', timeout=1.0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/site-packages/paramiko/client.py", line 296, in connect
    sock.connect(addr)
  File "/usr/lib64/python2.7/socket.py", line 222, in meth
    return getattr(self._sock,name)(*args)
socket.timeout: timed out