[Bug 882878] Re: With IPv6 disabled, openssh will not forward X connections

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On 2011-08-17T15:00:46+00:00 Diego-ercolani wrote:

User-Agent:       Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20100101
Firefox/5.0

When you disable ipv6 from the yast2 network, system correctly remove
the assignation of ipv6 addresses from everywhere but there is an
annoying bug in openssh that break the possibility to make X11 tunnels
because it seems that ssh try to bind X11 tunnel to an ipv6 address even
with ipv6 disabled causing this kind of message in /var/log/messages:

Aug 17 16:47:28 franz2011 sshd[6300]: error: Failed to allocate
internet-domain X11 display socket.

this can avoided configuring correctly the file /etc/ssh/sshd_config
with the parameter:

AddressFamily inet

and restarting sshd.
This is done in according to this bug reported to debian bugsystem:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=422327#20


Reproducible: Always

Steps to Reproduce:
1.
2.
3.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/882878/comments/0

------------------------------------------------------------------------
On 2011-12-05T13:58:14+00:00 Alberto-zacchetti wrote:

The same thing happens on my system. You can also fix it by entering the
-4 option in /etc/sysconfig/ssh, but it would be better to correct the
problem.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/882878/comments/4


** Changed in: openssh (Debian)
       Status: Unknown => New

** Changed in: openssh (openSUSE)
       Status: Unknown => Confirmed

** Changed in: openssh (openSUSE)
   Importance: Unknown => Medium

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https://bugs.launchpad.net/bugs/882878

Title:
  With IPv6 disabled, openssh will not forward X connections

Status in “openssh” package in Ubuntu:
  Confirmed
Status in “openssh” package in Debian:
  New
Status in “openssh” package in openSUSE:
  Confirmed

Bug description:
  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 at uscps002:/var/log# lsb_release -rd
  Description:	Ubuntu 11.10
  Release:	11.10
  root at uscps002:/var/log# 

  
  root at 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

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