Ubuntu
openssh package

  1. Bug #882878
  2. Comment #0

Comment 0 for bug 882878

Revision history for this message
gdahlman (gdahlman) wrote : With IPv6 disable openssh will on forward X connections

If you disable IPv6 in /etc/sysctl.conf sshd will not forward X11.

It logs the failue in /var/log/auth.log

Oct 27 18:49:26 uscps002 sshd[14722]: Accepted password for root from 172.20.10.50 port 60322 ssh2
Oct 27 18:49:26 uscps002 sshd[14722]: pam_unix(sshd:session): session opened for user root by (uid=0)
Oct 27 18:49:27 uscps002 sshd[14722]: error: Failed to allocate internet-domain X11 display socket.

Aparently the compiled sshd version will not try an ipv4 localhost if an ipv6 localhost does not exist.

Placing the following line in /etc/ssh/sshd_config fixes the issue

X11UseLocalHost no

root@uscps002:/var/log# lsb_release -rd
Description: Ubuntu 11.10
Release: 11.10
root@uscps002:/var/log#

root@uscps002:/var/log# uname -a
Linux uscps002 3.0.0-12-server #20-Ubuntu SMP Fri Oct 7 16:36:30 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux