[Info-vax] [7.3 VAX] XDM configuration

[chris]

On 11/17/22 22:45, Matthew R. Wilson wrote:
> On 2022-11-17, JKB <JKB at hilbert.invalid> wrote:
>> 	Hello,
>>
>> 	I have installed DECW (with SYS$UPDATE:DECW$TAILOR.EXE) on a
>> 	VAXserver (without graphic adapter) and started XDM.
>>
>> 	XDM seems to run:
>>
>> $ tcpip show service xdm
>> Service             Port  Proto    Process          Address            State
>>   
>> XDM                  177  UDP      TCPIP$XDM        0.0.0.0             Enabled
>> $
>>
>> 	On a remote workstation (Unix), nmap shows:
>>
>> ORT      STATE SERVICE
>> 23/tcp    open  telnet
>> 49152/tcp open  unknown
> 
> I think the XDM port 177 doesn't show up because NMAP doesn't scan for
> UDP ports by default.
> 
>> 	On client side, I try to connect to this VAX with
>> 	Xephyr -query fermat :1
>>
>> 	This last command runs fine as I can connect to another Unix station
>> 	with
>> 	Xephyr -query legendre :1
> 
> I have vague memories of some problems when I last tried this:
> 
> 1. The old version (and perhaps current versions) of the XDM/XDMCP
> implementation on VMS has trouble when you're querying it from anything
> other than X server display :0. I'm not sure you'll ever get it to work
> using display :1 with Xnest or Xephyr. I think you'd need to move your
> native X server to something other than :0 so that you can then have
> Xephyr listen on :0.
> 
> 2. Current/modern versions of X11 on Linux boxes are too new for OpenVMS
> 7.3. I've really only had luck if I intalled a backrev version of a
> Linux distribution such as RHEL/CentOS 6.
> 
> -Matthew
> 

I would use wireshark or tcpdump to monitor the src and dest hosts, so
you can analyse the traffic. Used recently here to debug a vnc 
connection, both network and local loopback, which xdmcp makes use of...

Chris