"su" - timeout for dbus/system_bus_socket if $DISPLAY set but unreachable

[Sven Uhlig <svenuhlig@web.de>]

Hello,

this is my first message to this list.

I noticed a little problem on my system after I installed the package
"virt-manager" and its dependencies on my system. One of the
dependencies is "dbus".

The problem is that "su" takes 25 seconds before it succeeds.

Using strace I think I identified the problem:
> connect(4, {sa_family=AF_FILE,
path="/var/run/dbus/system_bus_socket"}, 33) = 0
> ...
> poll([{fd=4, events=POLLIN}], 1, 25000) = 0 (Timeout) <25.028989>

The reasons seems to be my setup of the system.
Debian runs in a VirtualBox environment, headless and w/o X server.
I use ssh to connect to the system. (putty)
I use X forwarding to run X applications on the system.
The variable $DISPLAY gets set to 10.0.2.2:0 after ssh auth.
I only run the X server if it is required for running a X application.

I can skip the timeout if I do either of these two things:
Solution 1) run X server on 10.0.2.2 (Xming)
Solution 2) unset $DISPLAY

Is there something I can change in any of the configurations of "dbus"
or "su" to skip the timeout? Maybe don't use "dbus" for "su" at all?

System information:
> $ uname -a
> Linux baldur 3.2.0-4-amd64 #1 SMP Debian 3.2.39-2 x86_64 GNU/Linux
> $ dbus-daemon --version
> D-Bus Message Bus Daemon 1.6.8

Best regards
Sven.