Re: not getting login using xdmcp

[Harold L Hunt II <huntharo at msu dot edu>]

Andrew,

Andrew DeFaria wrote:
> Harold L Hunt II wrote:
>
> > Andrew,
> >
> > Andrew DeFaria wrote:
> >
> > > I have a similar problem. This is with a SuSE 8.2 installation. I had 
> > > Mandrake 9.1 installed before and managed to get XDMCP working. Can't 
> > > get it working with SuSE however and I'm pulling my hair out!
> > >
> > > I have nothing in my /var/log/messages nor /var/log/kdm.log files. 
> > > I'm using:
> > >
> > > $ xwin -query sonslinux -from adefaria
> > >
> > > X comes up but no login dialog box. XWin.log is attached.
> > >
> > > Any help would be appreciated.
> >
> >
> > How many network interfaces do you have?  
>
>
> 1

How about third-party (not from Microsoft) VPN or firewall software?

Also, do you have Windows XP with the SP2 beta that was announced a few 
days ago?  The SP2 beta may cause problems; I don't recommend using it 
until we have had a chance to look at it.

> > Find out the IP address of the interface that is actually 
> > communicating with sonslinux and make sure to specify that IP address 
> > in the -from parameter.  If you give it the wrong IP, it will cause 
> > the XDM serve to be unable to send messages back to XWin.exe
>
>
> Retried it with my IP address. Same problem.

Okay.

> > > XDM: too many retransmissions
> >
> >
> > This is your key log message from XWin.log.  The XDM support in 
> > XWin.exe is generic to all X Servers, so you can google for this 
> > message and try to find some help there.  My guess is that you either 
> > have a problem with the return address being incorrect (as I talk 
> > about above), or one of the following:
> >
> > 1) You have not enabled an XDM server on your Linux machine followed 
> > by a restart.
>
>
> I have (an aside, my understanding is that XDMCP runs on port 177. I try 
> to telnet to port 177 and get connection refused. Guess this is not 
> good). As you probably know XDMCP is not enabled by default. I have 
> changed the config files to allow it (at least I think I have) and have 
> not only restarted kdm but have rebooted the machine to no avail.

No, telnetting to port 177 will always fail.  Telnet connects to TCP 
ports; XDMCP listens on UDP port 177, not TCP port 177.  These are 
different ports and different protocols.

Your second point is interesting.  Have you confirmed that the graphical 
XDM login screen is showing on your server?  When you do a "ps | grep 
xdm", "ps | grep gdm", and "ps | grep kdm", does either of them return a 
matching process that is running?  If not, then you don't have one of 
the display managers running, which indicates a problem.

> > 2) You could also just not be running you linux machine at the correct 
> > run level, which would cause the XDM server to not even be started.
>
>
> Sonslinux sits right next to me. I am logged into a kde session right 
> now so I assume I'm at the proper run level.

Yes, but how did you login?  Did you login at a text prompt, then run 
startkde, or did you have a full-screen graphical login application 
(such as kdm)?

> > 3) You have not enabled remote XDMCP connections for the XDM server 
> > that you are running (followed by a restart):
> >
> > http://xfree86.cygwin.com/docs/faq/cygwin-xfree-faq.html#q-mandrake-8.1-xdmcp 
> >
> >
> > NOTE: The fact that the above link says "Mandrake" can be ignored... 
> > it was originally written when Mandrake started defaulting XDMCP to 
> > being disabled, which was closely followed by my realizing that almost 
> > all distributions started doing this.
>
>
> Yes. Let me read that and see what I find... (BTW this page answers my 
> soon to be next question of why I can't XDMCP to the Solaris box - Need 
> to use a font server! Thanks. BTW that XWin.log file may have been from 
> my attempt to XDMCP to the Solaris box. I've attached a new XWin.log).
>
> Enabled XDMCP in /opt/kde3/share/config/kdm/kdmrc (SuSE 8.2 - it's not 
> listed in your table -perhaps you would like to update that).

Yup, they only get listed if someone tells me where it is.  You told me, 
so I updated it.

> Note I also found the following in /etc/X11/xdm/xdm-config:
>
> ! SECURITY: do not listen for XDMCP or Chooser requests
> ! Comment out this line if you want to manage X terminals with xdm
> !
> !DisplayManager.requestPort:    0

This was probably not needed.  Once you change that line to enable 
XDMCP, the defaults for mosts distributions allow you to get a login 
screen from all remote machines.

> And as you can see I have commented that out. Both of these actions I 
> have done a few days ago and have since restarted kdm and even rebooted 
> sonslinux but the problem remains. This is why I'm pulling my hair out!

You are sure that you are running kdm, right?  You could be running gdm, 
in which case the kdmrc file would have no effect.

> Additionally I made sure the following appears in 
> /opt/kde3/share/config/Xaccess and /etc/X11/xdm/Xaccess:
>
> # The nicest way to run the chooser is to just ask it to broadcast
> # requests to the network - that way new hosts show up automatically.
> # Sometimes, however, the chooser can't figure out how to broadcast,
> # so this may not work in all environments.
> #
>
> *               CHOOSER BROADCAST       #any indirect host can get a 
> chooser

That should not be needed.  You might have goofed something up here. 
The default values allow any machine to get a login screen.

> Oh, BTW your link for Linux XDMCP HOWTO 
> (http://www.linuxdoc.org/HOWTO/XDMCP-HOWTO/) when clicked yeilds:
>
> Note:   You are trying to access The Linux Documentation Project website 
> using an old (and unsupported) URL. Please update your bookmarks to use 
> www.tldp.org <http://www.tldp.org> or en.tldp.org <http://en.tldp.org> 
> (if you just need the English documentation). Click to go directly to 
> the page you requested: http://en.tldp.org/HOWTO/XDMCP-HOWTO/

Thanks.  I fixed it.

The log file you sent doesn't seem to have anything useful in it.

Harold