Bug#1069236: openssh-server: X over ssh fails with "cannot open display"

I'm not using a hostname with ssh, I'm sshing directly to an IPv4 address.

*How* was it disabled?  net.ipv6.conf.all.disable_ipv6 = 1 in /etc/sysctl.conf

My point is that "AddressFamily any" should not fail to set $DISPLAY
if IPv6 is not available.

On Tue, Apr 23, 2024 at 5:38 AM Jonathan Dowland <[email protected]> wrote:
>
> On Thu, Apr 18, 2024 at 06:33:00AM -0500, allan wrote:
> > Resolved the issue by editing /etc/ssh/sshd_config and changing
> > #AddressFamily any
> > to
> > AddressFamily inet
>
> This is not a reasonable change to make to the default configuration,
> because it would mean that ssh did not work out of the box in IPv6
> environments.
>
> On Thu, Apr 18, 2024 at 07:53:52AM -0500, allan wrote:
> > More info - IPv6 is disabled on all four machines.  I think
> > "AddressFamily any" should have supported an IPv4 connection.
>
> *How* is it disabled? More information will be needed to figure out
> exactly what's gone on in your environment.
>
> I speculate that the hostnames you were trying to connect to were
> resolving as IPv6 addresses, and the connection failing because the
> hosts are rejecting IPv6 traffic. If that's right, the ultimate fix
> is to correct whatever name resolution is giving you the wrong
> addresses in your environment.
>
> If you are prepared to experiment, we might be able to drill down and
> check that. If so, can you
>
> 1) reverse the sshd_config change you made on at least one of the
>    hosts, and restart that sshd
>
> 2) assuming the troublesome host is named "myhost" in your environment
>    (substitute as appropriate), from your client machine, report the
>    result of running
>
>     getent hosts myhost
>     dig +short myhost
>     nslookup myhost
>     ping -c 1 myhost
>
>     (one or more of these commands may not exist on your machine)
>
> 2) re-attempt to connect from your client, this time passing -vv or
>    -vvv, and capture the logging output