[X2Go-User] Every connect from Ubuntu 18.04 client gives core dump

[Kees Bakker]

Bingo !!! Thanks Михайло.

That's it. Disabling ProxyCommand in /etc/ssh/ssh_config allows me
to get a remote session.

The FreeIPA installation puts these lines in /etc/ssh/ssh_config

     GlobalKnownHostsFile /var/lib/sss/pubconf/known_hosts
     PubkeyAuthentication yes
     ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h

Just disabling ProxyCommand is enough.

Of course it is not nice that you get a core dump when ProxyCommand
is present. That's a bug for sure (in x2go and/or in libssh.so).
-- Kees

On 10-10-19 21:36, Михайло Падалка wrote:
> **** EXTERNAL E-MAIL ****
>
> AFAIK FreeIPA modifies client SSH config when joining domain, particularly sets ProxyCommand (to pull SSH fingerprints from server), and maybe some other options.
>
> Maybe that changes are causing problem with X2GO.
>
> Ср, 9 жовт. 2019, 10:21 користувач Kees Bakker <keesb at ghs.com <mailto:keesb at ghs.com>> пише:
>
>     On 08-10-19 14:17, Stefan Baur wrote:
>     > Am 08.10.19 um 13:57 schrieb Kees Bakker:
>     >> I already tried that with another system.
>     >> Same result: core dumped.
>     > In that case, I would like to ask you to do fresh installs of Ubuntu
>     > 18.04 with X2GoServer and X2GoClient somewhere (say, two virtual
>     > machines), that aren't joined to your FreeIPA environment.  Just two
>     > plain and simple basic installations.  If it works there, then it's
>     > likely to be an issue with your particular setup.
>     Two virtual machines (with a reasonable fresh install) don't
>     give the problem. I haven't completed the whole test because I
>     needed to install LXDE, or MATE.
>     Most important conclusion is that the connection worked well.
>     No segfault.
>
>     >
>     > Also, did you try if using a different session type makes a difference?
>     > Say, a Desktop session of XFCE or MATE, or a single application
>     > LibreOffice session, ...
>     > Given your error message, it seems unlikely, but it's a quick check
>     > compared to the effort two new installs require.
>
>     I tried various desktops, all gave the "core dumped" message.
>
>     Can we draw the conclusion that it is the SSH connection?
>     How can I investigate this further? One thing I already tried was
>     to run the remote sshd in debug. I noticed that it uses different
>     connection methods between normal ssh and x2go.
>     -- 
>     Kees
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