[[!meta title="Tunneling the qemu or kvm vnc unix socket via ssh"]]

Perhaps you were searching for a way to tunnel the
[unix socket](http://en.wikipedia.org/wiki/Unix_domain_socket)
provided by
[qemu](http://www.qemu.org/)
or [kvm](http://www.linux-kvm.org/page/Main_Page)
for [vnc](http://en.wikipedia.org/wiki/Virtual_Network_Computing)
through an [ssh](http://www.openssh.com/) tunnel, too?
When I was searching for an answer, I found 
[ssvnc](http://www.karlrunge.com/x11vnc/ssvnc.html), which
I did not give a try, because I wanted to solve the problem
with [socat](http://www.dest-unreach.org/socat/) and ssh.

I started kvm on the **remote** machine using the following command:

    kvm -vnc unix:/home/services/vms/vnc-socket ...

Then I connected socat locally on the remote machine to test the settings:

    socat STDIO UNIX-CONNECT:/home/services/vms/vnc-socket

Which worked pretty fine. On the local side we need a listener on a
tcp port around port 5500+ (not a must, but the standard vnc port), which
can be created like that:

    socat STDIO TCP-LISTEN:5500

As reading and writing is not possible with a single pipe, one **cannot** just do
pipe into socat like this:

    ssh root@tee.schottelius.org "socat STDIO UNIX-CONNECT:/home/services/vms/vnc-socket" | socat STDIO TCP-LISTEN:5500

But socat has another nice option, the **EXEC** parameter, which solves the problem:

    socat TCP-LISTEN:5500 EXEC:'ssh root@tee.schottelius.org "socat STDIO UNIX-CONNECT:/home/services/vms/vnc-socket"'

And now I can connect locally via [tightvnc](http://www.tightvnc.com/):

    xtightvncviewer -encodings "copyrect tight hextile zlib corre rre raw" localhost:5500

I specify a different order for the encodings, because xtightvncviewer
prefers raw "encoding", if it connects to localhost, which is not desired
here.

And that's it, vnc connected to a unix socket from kvm tunneled through ssh!

[[!tag unix vm]]