Tunneling PyZMQ Connections with SSH

New in version 2.1.9.

You may want to connect ØMQ sockets across machines, or untrusted networks. One common way to do this is to tunnel the connection via SSH. IPython introduced some tools for tunneling ØMQ connections over ssh in simple cases. These functions have been brought into pyzmq as zmq.ssh under IPython’s BSD license.

PyZMQ will use the shell ssh command via pexpect by default, but it also supports using paramiko for tunnels, so it should work on Windows.

An SSH tunnel has five basic components:

  • server : the SSH server through which the tunnel will be created
  • remote ip : the IP of the remote machine as seen from the server (remote ip may be, but is not not generally the same machine as server).
  • remote port : the port on the remote machine that you want to connect to.
  • local ip : the interface on your local machine you want to use (default:
  • local port : the local port you want to forward to the remote port (default: high random)

So once you have established the tunnel, connections to localip:localport will actually be connections to remoteip:remoteport.

In most cases, you have a zeromq url for a remote machine, but you need to tunnel the connection through an ssh server. This is

So if you would use this command from the same LAN as the remote machine:


to make the same connection from another machine that is outside the network, but you have ssh access to a machine server on the same LAN, you would simply do:

from zmq import ssh
ssh.tunnel_connection(sock, "tcp://", "server")

Note that "server" can actually be a fully specified "user@server:port" ssh url. Since this really just launches a shell command, all your ssh configuration of usernames, aliases, keys, etc. will be respected. If necessary, tunnel_connection() does take arguments for specific passwords, private keys (the ssh -i option), and non-default choice of whether to use paramiko.

If you are on the same network as the machine, but it is only listening on localhost, you can still connect by making the machine itself the server, and using loopback as the remote ip:

from zmq import ssh
ssh.tunnel_connection(sock, "tcp://", "")

The tunnel_connection() function is a simple utility that forwards a random localhost port to the real destination, and connects a socket to the new local url, rather than the remote one that wouldn’t actually work.

See also

A short discussion of ssh tunnels: http://www.revsys.com/writings/quicktips/ssh-tunnel.html