[Info-vax] [7.3 VAX] XDM configuration

[Bill Gunshannon]

On 11/18/22 11:16, chris wrote:
> On 11/18/22 08:11, JKB wrote:
>> Le 17-11-2022, chris <chris-nospam at tridac.net> a écrit :
>>>
>>> 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...
>>
>>     Xephyr runs fine. I can access to legendre.systella.fr with:
>>     Xephyr :1 -listen tcp -query legendre
>>
>>     If I tri to access to fermat (this VAX), I only obtain a black
>>     screen. But it seems to answer to request:
>>
>> Root hilbert:[~] > tcpdump -p -i eth0 -vvv host fermat
>> tcpdump: listening on eth0, link-type EN10MB (Ethernet), snapshot 
>> length 262144 bytes
>> 09:06:58.114604 IP (tos 0x0, ttl 64, id 39927, offset 0, flags [DF], 
>> proto UDP (17), length 35)
>>      hilbert.systella.fr.39124 > fermat.systella.fr.xdmcp: [udp sum 
>> ok] UDP, length 7
>> 09:06:58.246108 IP (tos 0x0, ttl 30, id 37659, offset 0, flags [DF], 
>> proto UDP (17), length 75)
>>      fermat.systella.fr.xdmcp > hilbert.systella.fr.39124: [udp sum 
>> ok] UDP, length 47
>> 09:06:58.246283 IP (tos 0x0, ttl 64, id 39952, offset 0, flags [DF], 
>> proto UDP (17), length 134)
>>      hilbert.systella.fr.39124 > fermat.systella.fr.xdmcp: [bad udp 
>> cksum 0x96a6 -> 0x899a!] UDP, length 106
>> 09:06:59.483783 IP (tos 0x0, ttl 30, id 37660, offset 0, flags [DF], 
>> proto UDP (17), length 80)
>>      fermat.systella.fr.xdmcp > hilbert.systella.fr.39124: [udp sum 
>> ok] UDP, length 52
>> 09:06:59.483837 IP (tos 0x0, ttl 64, id 40214, offset 0, flags [DF], 
>> proto UDP (17), length 57)
>>      hilbert.systella.fr.39124 > fermat.systella.fr.xdmcp: [bad udp 
>> cksum 0x9659 -> 0xb434!] UDP, length 29
>> 09:07:01.485945 IP (tos 0x0, ttl 64, id 40658, offset 0, flags [DF], 
>> proto UDP (17), length 57)
>>      hilbert.systella.fr.39124 > fermat.systella.fr.xdmcp: [bad udp 
>> cksum 0x9659 -> 0xb434!] UDP, length 29
>> 09:07:05.488721 IP (tos 0x0, ttl 64, id 41488, offset 0, flags [DF], 
>> proto UDP (17), length 57)
>>      hilbert.systella.fr.39124 > fermat.systella.fr.xdmcp: [bad udp 
>> cksum 0x9659 -> 0xb434!] UDP, length 29
>> 09:07:06.672721 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has 
>> fermat.systella.fr tell hilbert.systella.fr, length 28
>> 09:07:06.702501 ARP, Ethernet (len 6), IPv4 (len 4), Reply 
>> fermat.systella.fr is-at 08:00:2b:7a:39:2e (oui Unknown), length 46
>> ^C
>> 9 packets captured
>> 633 packets received by filter
>> 0 packets dropped by kernel
>>
>>     Of course, xdm is running :
>>
>> $ pipe show sys | search SYS$INPUT XDM
>> 00000113 TCPIP$XDM_1     LEF     10      532   0 00:00:10.72      
>> 2123   2109  N
>>
>>     I suppose my xdm configuration is faulty somewhere.
>>
>>     Best regards,
>>
>>     JKB
>>
> 
> 
> Looks like you are getting a reply from the third enquiry, then the last
> three enquiries are being ignored by the xdmcp host. First thing I would
> do is to temporarily disable all X security, as that may be enabled by
> default. Other than that, no idea, other a config issue. Also, wireshark
> to look at packet contents in depth...
> 
> Chris
> 
> 

On another note...

Unless your running a lab full of X-terminals why do you even
need XDM?  Why not just set the VAX to start sessions as soon
as it sees the remote end appear?

bill