SSH X11 forwarding not working

Problem

X11 forwarding via SSH is not working and gives following error in SYSLOG:

Jan 10 08:36:50 juno sshd[23231]: error: Failed to allocate internet-domain X11 display socket.

Solution

Looks like the fix for CR 6684003 breaks sshd’s ability to bind to a local socket for X forwarding. bind() returns EADDRNOTAVAIL for every bind call to ::1 for ports 6010->6999, but never tries IPv4 localhost addresses.

So if you do not have an IPv6 interface you will get this error. Fix it by either:

• Adding AddressFamily inet to the /etc/ssh/sshd_config and restart sshd
• Enable IPv6 on the loopback interface lo0