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

[ChristianEhrhardt]

Hi Peter,
while looking into an issue (on Ubuntu) I found that you solved it for SuSe
a long time ago in [1] via [2].
That change seems to be carried forward since, with the last revision being
[3].

I wondered if it was tried to bring the change upstream?
I didn't find any reference, but this is from long ago so I hoped you might
know some more context.
Was it discussed, nack-ed for a reason or is there anything else why this
isn't upstream after all the years?
Before adopting your or a similar change it would be nice to get that
context info.

[1]: https://bugzilla.novell.com/show_bug.cgi?id=712683
[2]: https://bugzilla.novell.com/attachment.cgi?id=580591&action=diff
[3]:
https://build.opensuse.org/package/view_file/openSUSE:Factory/openssh/openssh-7.2p2-X_forward_with_disabled_ipv6.patch?expand=1

P.S. This is the mail to Peter with the bug on CC, to "log" it there.

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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:
  Fix Released

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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