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Accepted
Andrey Nikolaev
Asked: 2024-11-02 19:36:25 +0800 CST

slow ssh connection when enabling x11 forwarding (in local network from selected machines)

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I have virtual machine on my local network (1G), which I use as linux development enviroment. I connect to this machine from my Windows 11 PC using VCXsrv and x11 forwarding.

Recenntly all application started opening extremely slowly, new windwos within running application oppening with lag, and even cursor in mc moving with lag.

But this is only happening when I connect with ssh -Y and only when connecting from windows or ubuntu LTS.

  • If I connect from windows (VCXsrv) - lag
  • If I connect from ubuntu (24.04.1 wayland kernel 6.8.0-48-generic) - lag
  • If i connect without X11 forwarding - mc cursor acts normaly, most likely no lag
  • If i connect from OpenSuse Tumbleweed (241025 KDE 6.2.2 wayland kernel 6.11.5-1-default) - everything working as expected even with x11 forwarding, no lag

Host machine is manjaro, fully updated. Linux clients installed in VMs on windows machine.

At the time when I started experiencing lags I have installed JDK on host machine, but i don't know if it can have such effect.

SSH versions:

  • host machine - OpenSSH_9.8p1, OpenSSL 3.3.2 3 Sep 2024
  • Windows - OpenSSH_for_Windows_9.5p1, LibreSSL 3.8.2
  • Ubuntu - OpenSSH_9.6p1 Ubuntu-3ubuntu13.5, OpenSSL 3.0.13 30 Jan 2024
  • OpenSuse - OpenSSH_9.9p1, OpenSSL 3.1.4 24 Oct 2023
windows

1 Answers

  1. Best Answer

    I was able to return to normal latency with

    ssh -Y -o ObscureKeystrokeTiming=no <server>

    Found answer in this reply: https://serverfault.com/a/1159925/276240

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