It seems the option "KDM should listen to XDMCP requests" is disable!

Could you please change the line "Enable=false" to "Enable=true" from the 
section [Xdmcp] in /etc/X11/xdm/kdmrc and try again? Thanks

please make sure that you have to restart kdm after changing the kdmrc!

> [Xdmcp]
> Enable=true

works fine. but this is NOT the bug reported about "indirect" requests and no
answers to the "forward_query".

if you 
Xnest :1 -query "C"
everything works fine, but 
Xnest :1 -indirect "B"
"C" is listed but the connection fails as discribed.

Fedora apologizes that these issues have not been resolved yet. We're
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For what it's worth, I can report exactly the same trouble symptom
that Mr. Dorfmeister describes, except that I am running Fedora *8*
and gdm.

Specifically: Fedora 8, kernel-2.6.24.4-64.fc8 with gdm-2.20.3-1.fc8.

In my case the forward queries do not even go to the correct host, e.g.,
with my internal net being 192.168.200.0/24 and the selected host
being 192.168.200.4, wireshark shows the forward queries being sent
to addresses like 112.197.67.9, 53.0.77.101, 53.0.67.9, etc. Something
in the chooser or some underlying library is generating garbage
destination addresses.

As Mr. Dorfmeister describes, the chooser was working with gdm
in Fedora 6. Now it's broken in Fedora 8. I use gnome and haven't
tested with kde/kdm.

thanks for your update. changing version to '8'

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Fedora 8 changed to end-of-life (EOL) status on 2009-01-07. Fedora 8 is 
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Thank you for reporting this bug and we are sorry it could not be fixed.

Hi,

I tried cloning this bug to make a new posting out of it, but
nothing happened, so let me try just add a comment.

This bug occurs identically as described above in Fedora 10
*and* Fedora 11.

Since gdm no long supports xdmcp, I am now using kdm like the
original reporter.

To summarize:
 1) kdm correctly configured on machine A and machine B
 2) At the graphical login screen of either, select menu->remote login,
    and see A and B in the chooser list
 3) Select the other machine
 4) Successful connection occurs, and login to the remote machine is possible

So far, so good. Now the failure scenario:
 2) Login to either machine, from e.g., a gnome-terminal, run
      Xephyr -indirect localhost :1
      (or substitute the local machine's name for localhost)
    and see A and B in the chooser list
 3) Select the other machine
 4) Xephyr screen goes grey with an X cursor and stays that way
    until the connection attempt times out, then the chooser reappears.

During the timeout period, wireshark shows FORWARD_QUERY packets going
to the remote machine, and wireshark running on the remote machine shows
the arrival of the FORWARD_QUERYs. The remote machine generates no response.

When the remote connection is attempted from the login screen menu as in 
1-4) earlier, the local machine is not sending FORWARD_QUERYs, it is sending
a direct query to the remote.

This bug has now been demonstrated using kdm and, previously, gdm, spanning
multiple versions of Fedora over a three year period.

The three conspicuous features of this bug are:
  * recipients of xdmcp FORWARD_QUERYs don't seem to know what to do with them
  * a connection attempt via kdm from the login screen results in a direct
    query while an attempt via kdm from a nested server such as Xnest or
    Xephyr results in a forward query. Whey the different behavior?
  * Xnest or Xephyr both work when a direct query is forced on the
    command line, e.g.,
      Xephyr -query other_machine :1

Please keep this bug alive. Broken xdmcp/chooser in a nested server is
a real sore spot.

Bug persists as of january 2012, with EL6 (Scientific Linux 6.1)
It manifests as Dennis has wrote in previous comment.

Maybe this should be fixed after 6 years? ...