Connecting to a modern Xserver with an old client
I'm trying to connect an old HP logic analyzer (circa 1998) to a modern Xorg server. The error message I get is ... Xlib: connection to "192.168.1.1:1.0" refused by server Unable to open window on "192.168.1.1:1.0" I have executed "xhost +" to allow access by any client and I am able to generate an xterm window from another modern computer on the network "xterm -display 192.168.1.1:1.0". I have no way to know what the logic analyzer is actually trying to do or what it doesn't like. On the X server side, it's started by gdm & I can't find out how to change the log level of Xorg (I think there is some gdm code that starts Xorg) ... /usr/libexec/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -listen tcp -background none -noreset -keeptty -novtswitch -verbose 7 -core What might be the issue with this old X client authenticating with a modern X server?
Re: Connecting to a modern Xserver with an old client
To answer Grant's question. Yes, I had added the X ports but I've now turned off the firewall just to be sure. Here is the wireshark conversation. I'm not knowledgeable enough to recognize the issue.. 10.0192.168.1.16192.168.1.1TCP606915 → 6001 [SYN] Seq=0 Win=0 Len=0 MSS=1416 20.000165997192.168.1.1192.168.1.16TCP586001 → 6915 [SYN, ACK] Seq=0 Ack=1 Win=64240 Len=0 MSS=1460 30.005196101192.168.1.16192.168.1.1TCP606915 → 6001 [ACK] Seq=1 Ack=1 Win=1416 Len=0 40.008854195192.168.1.16192.168.1.1X1166Initial connection request 50.008914324192.168.1.1192.168.1.16TCP546001 → 6915 [ACK] Seq=1 Ack=13 Win=64228 Len=0 60.009029932192.168.1.1192.168.1.16TCP626001 → 6915 [PSH, ACK] Seq=1 Ack=13 Win=64228 Len=8 [TCP segment of a reassembled PDU] 70.009086172192.168.1.1192.168.1.16X11110Initial connection reply 80.009149782192.168.1.1192.168.1.16TCP546001 → 6915 [FIN, ACK] Seq=65 Ack=13 Win=64228 Len=0 90.017057921192.168.1.16192.168.1.1TCP60[TCP ZeroWindow] 6915 → 6001 [ACK] Seq=13 Ack=66 Win=0 Len=0 100.019632130192.168.1.16192.168.1.1TCP60[TCP ZeroWindow] 6915 → 6001 [ACK] Seq=13 Ack=66 Win=0 Len=0 110.023341315192.168.1.16192.168.1.1TCP60[TCP ZeroWindow] 6915 → 6001 [ACK] Seq=13 Ack=66 Win=0 Len=0 120.083569102192.168.1.16192.168.1.1TCP606915 → 6001 [FIN, PSH, ACK] Seq=13 Ack=66 Win=0 Len=0 130.083647415192.168.1.1192.168.1.16TCP546001 → 6915 [ACK] Seq=66 Ack=14 Win=64228 Len=0 Also, yes the X display is 1 on this server.
Re: Connecting to a modern Xserver with an old client
Yes, xtrace looks just like what I need but I cant't get it to work on remote connections. If I run "xterm -display :9.0" from the machine where X server and xtrace (x11trace on Fedora) runs it works (and I see X11 conversations) but If I try from another machine on the network (xterm -display 192.168.1.1:9.0), I cannot connect. Is there some switch I need so that remote connections are responded to. From what I read, xtrace should pick up the current auth settings (xhost +), so this should not be the issue I think. Michael On Sunday, July 23, 2023 at 05:58:30 AM EDT, Carsten Haitzler wrote: On Sat, 22 Jul 2023 20:47:03 +0000 (UTC) Michael K said: > > To answer Grant's question. Yes, I had added the X ports but I've now turned > off the firewall just to be sure. Here is the wireshark conversation. I'm > not knowledgeable enough to recognize the issue.. > > 10.0192.168.1.16192.168.1.1TCP606915 → 6001 > [SYN] Seq=0 Win=0 Len=0 MSS=1416 > 20.000165997192.168.1.1192.168.1.16TCP586001 → 6915 > [SYN, ACK] Seq=0 Ack=1 Win=64240 Len=0 MSS=1460 > 30.005196101192.168.1.16192.168.1.1TCP606915 → 6001 > [ACK] Seq=1 Ack=1 Win=1416 Len=0 > 40.008854195192.168.1.16192.168.1.1X1166Initial > connection request > 50.008914324192.168.1.1192.168.1.16TCP546001 → 6915 > [ACK] Seq=1 Ack=13 Win=64228 Len=0 > 60.009029932192.168.1.1192.168.1.16TCP626001 → 6915 > [PSH, ACK] Seq=1 Ack=13 Win=64228 Len=8 [TCP segment of a reassembled PDU] > 70.009086172192.168.1.1192.168.1.16X11110Initial > connection reply > 80.009149782192.168.1.1192.168.1.16TCP546001 → 6915 > [FIN, ACK] Seq=65 Ack=13 Win=64228 Len=0 > 90.017057921192.168.1.16192.168.1.1TCP60[TCP > ZeroWindow] 6915 → 6001 [ACK] Seq=13 Ack=66 Win=0 Len=0 > 100.019632130192.168.1.16192.168.1.1TCP60[TCP > ZeroWindow] 6915 → 6001 [ACK] Seq=13 Ack=66 Win=0 Len=0 > 110.023341315192.168.1.16192.168.1.1TCP60[TCP > ZeroWindow] 6915 → 6001 [ACK] Seq=13 Ack=66 Win=0 Len=0 > 120.083569102192.168.1.16192.168.1.1TCP606915 → 6001 > [FIN, PSH, ACK] Seq=13 Ack=66 Win=0 Len=0 > 130.083647415192.168.1.1192.168.1.16TCP546001 → 6915 > [ACK] Seq=66 Ack=14 Win=64228 Len=0 > > Also, yes the X display is 1 on this server. OK - looks like it's connecting and actually talking, so your next port of call might be some x11 protocol analysis. xtrace. xscope are some of these. I'm wondering if it's trying to create a colormapped window with a private colormap assuming a pseudocolor display (or using a pseudocolor visual). given an old enough app it may never have worked on truecolor displays. -- - Codito, ergo sum - "I code, therefore I am" -- Carsten Haitzler - ras...@rasterman.com
Re: Connecting to a modern Xserver with an old client
OK, I got xtrace to work ("$ x11trace -n -D 192.168.1.1:10.0" & have the
instrument connect to display 10.0) and it was more instructive...
Got connection from 192.168.1.16:6144
000:<: am msb-first want 11:0 authorising with '' of length 0
000:>: Failed, version is 11:0 reason is ' Prohibited client endianess, see
the Xserver man page '.
So as per the man page I added +byteswappedclients to the Xorg command line and
it works!
The HP instrument runs a Motorola MC68020 (big endian) & my RPI ARM is set up
as little endian. Back in the day I think most machines were big endian (before
*nix on Intel processors became a thing)
Thanks Carsten & Grant for the clues and debugging advice 8-)
Michael
