X11 forwarding and iptables question

[John Sellens]

If X apps work for you locally, then they should also work with X11
forwarding over ssh, unless you have very strange iptables settings
(e.g. rules on lo0/127.0.0.1/localhost).

Check the remote end's sshd_config file to make sure that X11Forwarding
is allowed.  My sshd_config(5) man page says that the default is no.

Check your DISPLAY environment variable in your ssh session (via echo
$DISPLAY).  Ssh should set it to something like localhost:10.0 if
forwarding is working.

Check that the remote end has an xauth(1) command.

See if verbose ssh (with -v) tells you anything interesting.

Hope that helps!

John



| I recently locked down my ports using some iptables rules to DROP all INPUT 
| and FORWARD packets and then accept only on certain ports.
| 
| My most of my stuff is working as expected except for X11 forwarding (ie. by 
| logging in with ssh -X and running stuff like xclock).
| 
| I noticed that ports 177 and 6000:6007 are X11 related.   I opened these up on 
| the INPUT chain but X11 forwarding still doesn't work.
| 
| What iptable rule should I be invoking to allow X11 forwarding?
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