Solaris 10 ssh XForward problems

We've found that a number of Solaris 10 U4 machines that have been recently patched will no longer allow X11 forwarding from SSH. It turns out this is because sshd is trying to use the ipv6 localhost (::1) by default which we don't have enabled.

The error message given in /var/adm/messages is:

Jun 24 16:56:43 tart sshd[6788]: [ID 800047 auth.error] error: Failed to allocate internet-domain X11 display socket.

A quick fix is to run:

ifconfig lo0 inet6 plumb up

and to ensure the change persists across reboots:

touch /etc/hostname6.lo0

The issue seems to be caused by patch 126133-03.

Contact: site@spod.cx