I was setting up a new 11.4 system and disabled ip6 as we don’t use it. After that I couldn’t get X11 forwarding working.
After searching around for a while, I found this topic
http://forums.opensuse.org/english/get-technical-help-here/network-internet/398918-cant-enable-
ssh-x11-forwarding.html which at the end mentions enabling ip6. Magically, after doing that and rebooting I can now do X11 forwarding again.
Just seems strange that IP6 is needed for X11 forwarding.
afaik, you don’t!
one common problem for X11 forwarding not working, is the unavailability of xauth in the remote system.
I can confirm this! I think I saw similar bugs in some Solaris systems by Googling.
Actually it is a known bug in openSUSE 11.4! See the link to bugzilla.
According to a post in bugzilla https://bugzilla.novell.com/show_bug.cgi?id=686477 you need not enable IPv6 to make X11 forwarding work. It is sufficient to edit /etc/ssh/sshd_config and set
AddressFamily inet
instead of #AddressFamily any
This worked for me.