Re: Logging off an X session closes all ssh -X connections started previously from outside X
On Thu, 4 May 2023 at 19:07, zithro <slack@rabbit.lu> wrote:
> this is a rather strange problem, I hope the title is explicit enough.
Subject: Logging off an X session closes all ssh -X connections
started previously from outside X
> Here is what happens chronologically :
>
> 1. I start various SSH connections to a host, some normal, some with X
> forwarding, like that: "ssh user@host" and "ssh -X -n user@host GUI_APP"
> (like firejail firefox, firejail thunderbird, etc). There's no user
> connected under X yet, only the greeter is displayed.
>
> 2. using VNC or rdesktop, I then log on to X on the machine, do some
> stuff, then hit "log off" from the desktop menu.
> Immediately, ALL the previous SSH connections started in step 1 get
> closed, hence all the shells and the GUI apps (firefox, etc) !
>
> Everything is done using the same local and remote users (same UID but
> different names). sshd is the parent process of all my remote SSH sessions.
>
> I don't get how apps and shells NOT started via the X session, moreover
> previously to its creation, are closed when the X session closes, what's
> happening here ?!
> As the outcome is the same with VNC and rdesktop, I guess the problem is
> lying in the OS. Could it be related to logind ? Or an SSH(d) setting ?
That sounds like what is documented here, with the solution at the end:
$ apt show dbus-user-session
Package: dbus-user-session
Version: 1.12.24-0+deb11u1
[... some output snipped for brevity ...]
Description: simple interprocess messaging system (systemd --user integration)
D-Bus is a message bus, used for sending messages between applications.
Conceptually, it fits somewhere in between raw sockets and CORBA in
terms of complexity.
.
On systemd systems, this package opts in to the session model in which
a user's session starts the first time they log in, and does not end
until all their login sessions have ended. This model merges all
parallel non-graphical login sessions (text mode, ssh, cron, etc.), and up
to one graphical session, into a single "user-session" or "super-session"
within which all background D-Bus services are shared.
.
Multiple graphical sessions per user are not currently supported in this
mode; as a result, it is particularly suitable for gdm, which responds to
requests to open a parallel graphical session by switching to the existing
graphical session and unlocking it.
.
To retain dbus' traditional session semantics, in which login sessions
are artificially isolated from each other, remove this package and install
dbus-x11 instead.
[...]
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