[Bug 657302] Re: ssh X11 forwarding does not work

[H.-Dirk Schmitt]

*** This bug is a duplicate of bug 882878 ***
    https://bugs.launchpad.net/bugs/882878

** This bug has been marked a duplicate of bug 882878
   With IPv6 disabled, openssh will not forward X connections

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https://bugs.launchpad.net/bugs/657302

Title:
  ssh X11 forwarding does not work

Status in “openssh” package in Ubuntu:
  Won't Fix

Bug description:
  I have problems with X11 forwarding via SSH both with lucid and maverick. On both of these systems it simply does not work
  saying (for example):

  xterm Xt error: Can't open display: 
  xterm:  DISPLAY is not set

  In /var/log/auth.log I can find this:

  Oct  9 13:46:45 oxygene sshd[11122]: error: Failed to allocate
  internet-domain X11 display socket.

  After trying to strace the sshd process, I found things like this:

  11122 bind(10, {sa_family=AF_INET6, sin6_port=htons(6010),
  inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0,
  sin6_scope_id=0}, 28) = -1 EADDRNOTAVAIL (Cannot assign requested
  address)

  It's strange for me, since I've disabled IPv6 everywhere, but still it
  want to use it for some unknown reason ...

  I even have -4 option in /etc/default/ssh but it does not help.

  HOWEVER, if I stop ssh daemon and launch it "by hand" /usr/sbin/sshd
  -4 then it works nicely! It's interesting that init script (or
  upstart?) script of sshd does not honor /etc/default/ssh it seems ...
  Or it shouldn't do that in maverick anymore?

  Yes, I know that problem is caused not having IPv6 in my system by
  will, but I haven't known that I am forced to have configured IPv6 it
  was not compulsory in previous versions of Ubuntu distros. Is it
  possible to use Ubuntu in a normal way (without dirty hacks) if I
  don't want IPv6 at all? On my network there is no IPv6 capable
  equipment, so it's totally pointless to have it for any reason but
  still it does introduces possible security holes etc, I think the best
  practice not to have _anything_ configured which is not used/needed to
  avoid resource wasting and maybe even security problems. Like in
  OpenBSD where the default install is very minimal that's why that only
  2 remote holes in the default install since X ages :) :)

  lo        Link encap:Local Loopback  
            inet addr:127.0.0.1  Mask:255.0.0.0
            UP LOOPBACK RUNNING  MTU:16436  Metric:1
            RX packets:1777 errors:0 dropped:0 overruns:0 frame:0
            TX packets:1777 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:0 
            RX bytes:6642772 (6.6 MB)  TX bytes:6642772 (6.6 MB)

  ProblemType: Bug
  DistroRelease: Ubuntu 10.10
  Package: openssh-server 1:5.5p1-4ubuntu4
  ProcVersionSignature: Ubuntu 2.6.35-22.33-generic 2.6.35.4
  Uname: Linux 2.6.35-22-generic i686
  NonfreeKernelModules: nvidia
  Architecture: i386
  Date: Sat Oct  9 13:52:29 2010
  EcryptfsInUse: Yes
  ProcEnviron:
   LANGUAGE=en_US:en
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: openssh

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