Is there anything missing when forwarding my X11 connections?

[Vladimir Dergachev]

This reminds me of the difference between ssh -X and ssh -Y options, maybe 
a look at ssh code will give you ideas.

best

Vladimir Dergachev

On Fri, 7 Feb 2025, Christophe Lohr wrote:

> Hello,
>   Please excuse the naivety of my question; I'm trying to understand how things work.
> 
> I try to forward a tcp X11 connection to the server's unix socket:
>   $ socat  TCP-LISTEN:6001,fork UNIX-CONNECT:/tmp/.X11-unix/X0
> 
> Then I can use it:
>   $ DISPLAY=localhost:1 xeyes
> 
> It works well... but only for simple applications (xlogo xeyes xclock xmessage xnest...)
> Surprisingly, this does not works for more complex applications (Xephyr wireshark ...)
> These applications stop, seemingly waiting for an event that doesn't come.
> Increasing socat's verbosity level doesn't help me to understand, nor does strace ltrace xtrace ...
> 
> Well, this seems relating to the MIT-SHM extension.
> My assumption: If the server thinks the client is local (due to the use of a unix socket), it activates the MIT-SHM extension without further preliminary checks (and tries to send ancillary data
> (shm keys or file descriptor?) via the unix socket?). Right?
> 
> As a workarround, I have to generate an "untrusted" xauth cookie.
> Is there a better way?
> 
> (Note: I'm a fan of network transparency!
> A next time we'll talk about vsock;-) )
> 
> Best regards
> Christophe
>