remote X connections

[Christian Groessler]

Hi,

recently I've updated from FC24 to FC27. Since then remote X connections 
don't work anymore. For my environment I'm typically starting an xterm 
shell from another computer displaying on my workstation.

When using "gdm", remote X access is en-/disabled with the
"DisallowTCP" 
setting in "/etc/gdm/custom.conf".

Now, there is a trap door. Xorg changed the default for remote 
connections a few releases ago.
Old releases listened on the network unless "-nolisten tcp" was 
specified. Newer releases only listen on the network
if "-listen tcp" is specified on the command line to start the X server.

This means that gdm either needs to add "-nolisten tcp" (old server, 
DisallowTCP=true) or "-listen tcp" (new server, DisallowTCP=false)
to the X server command line.

This is handled by conditional compilation in gdm (depending on a 
HAVE_XSERVER_THAT_DEFAULTS_TO_LOCAL_ONLY define).

The setting for this define is determined in configure.ac, lines


dnl 
---------------------------------------------------------------------------
dnl - Check if Xorg is new enough to require '-listen tcp' (1.17)
dnl 
---------------------------------------------------------------------------

if $PKG_CONFIG --atleast-version=1.17 xorg-server; then
    AC_DEFINE([HAVE_XSERVER_THAT_DEFAULTS_TO_LOCAL_ONLY], [], [XServer 
disables tcp access by default])
fi


Now, my installed gdm seems to think that my Xserver doesn't default to 
"local only". If I set DisallowTCP to true, it adds
a "-nolisten tcp" parameter to the X command line. While it shouldn't 
add anything in this case. If I set DisallowTCP to false
it doesn't add anything to the command line (where it should add 
"-listen tcp").

On my system, running the test above returns correct results:


$ pkg-config --atleast-version=1.17 xorg-server ; echo $?
0
$


I've build the gdm RPM from source on my local machine, installed it, 
and, hey, now everything works as expected.

So I guess that the machine used to build the official packages still 
has an old X server installed. If that's true,
could this be fixed?

regards,
chris

[Michal Schmidt]

On 11/30/2017 01:39 PM, Christian Groessler wrote:
>  This is handled by conditional compilation in gdm (depending on a
>  HAVE_XSERVER_THAT_DEFAULTS_TO_LOCAL_ONLY define).
>  
>  The setting for this define is determined in configure.ac, lines[...]
>   if $PKG_CONFIG --atleast-version=1.17 xorg-server; then 
>  AC_DEFINE([HAVE_XSERVER_THAT_DEFAULTS_TO_LOCAL_ONLY], [], [XServer
>  disables tcp access by default]) fi[...]
>  On my system, running the test above returns correct results:
>  
>  $ pkg-config --atleast-version=1.17 xorg-server ; echo $? 0 $
>  
>  
>  I've build the gdm RPM from source on my local machine, installed it,
>  and, hey, now everything works as expected.
>  
>  So I guess that the machine used to build the official packages still
>  has an old X server installed. If that's true, could this be fixed? 
Looks like gdm is missing BuildRequires: pkgconfig(xorg-server)
Please report a bug for gdm in Bugzilla.

Michal

[Ray Strode]

================================================================================
     gdm-3.26.2.1-3.fc27
================================================================================
   Update ID: FEDORA-2017-e8628817ff
Content Type: rpm
     Release: Fedora 27
      Status: pending
        Type: bugfix
       Karma: 0
   Autokarma: True  [-3, 3]
     Request: testing
       Notes: Add buildrequires for X server so DisableTcp config option works
            : properly.
   Submitter: rstrode
   Submitted: 2017-11-30 14:31:29
    Comments: bodhi - 2017-11-30 14:31:29 (karma 0)
              This update has been submitted for testing by
              rstrode.

  https://bodhi.fedoraproject.org/updates/FEDORA-2017-e8628817ff

[Christian Groessler]

On 11/30/17 13:57, Michal Schmidt wrote:

>  Looks like gdm is missing BuildRequires: pkgconfig(xorg-server)
>  Please report a bug for gdm in Bugzilla. 

Can I cite your email on this bug report. What exactly will this 
"BuildRequires" change accomplish?

regards,
chris

[Michal Schmidt]

On 12/01/2017 04:44 PM, Christian Groessler wrote:
>  On 11/30/17 13:57, Michal Schmidt wrote:
>  
> > Looks like gdm is missing BuildRequires: pkgconfig(xorg-server) 
> > Please report a bug for gdm in Bugzilla.
>  
>  
>  Can I cite your email on this bug report. What exactly will this
>  "BuildRequires" change accomplish? 
No need to file the bugreport. Ray Strode already fixed it.
The added BuildRequires ensures the correct package is installed
in the buildroot to make the pkg-config test in gdm's configure.ac
work.

Michal

[Jan Kratochvil]

On Thu, 30 Nov 2017 13:39:16 +0100, Christian Groessler wrote:
>  This is handled by conditional compilation in gdm (depending on a
>  HAVE_XSERVER_THAT_DEFAULTS_TO_LOCAL_ONLY define). 
gdm ignores DisallowTCP=false on F22
https://bugzilla.redhat.com/show_bug.cgi?id=1226084

FYI I had a problem with it around those versions F-22..F-24 but it does work
for me for several releases now incl. F-27.


Jan

[Christian Groessler]

On 11/30/17 13:58, Jan Kratochvil wrote:
>  On Thu, 30 Nov 2017 13:39:16 +0100, Christian Groessler wrote:
> > This is handled by conditional compilation in gdm (depending on a
> > HAVE_XSERVER_THAT_DEFAULTS_TO_LOCAL_ONLY define).
>  gdm ignores DisallowTCP=false on F22
>  https://bugzilla.redhat.com/show_bug.cgi?id=1226084
>
>  FYI I had a problem with it around those versions F-22..F-24 but it does work
>  for me for several releases now incl. F-27. 

Hmm, for me it doesn't work. I had FC24 before (where it worked, but
I don't remember if I had local tweaks. I found the 
gdm-3.18.2-2.fc23.src.rpm
on my machine, maybe I did some changes to it in order to get it to work.
Really don't remember.

But after upgrading from FC-24 to FC-26 it stopped working. Then I upgraded
to FC-27, still not working.

regards,
chris