Xlibre [LWN.net]

Xlibre

Posted Jun 17, 2025 1:50 UTC (Tue) by raven667 (subscriber, #5198)
In reply to: Xlibre by pizza
Parent article: Ubuntu 25.10 to drop support for GNOME on Xorg

> openssh's -X option claims to support interacting with X11 "Security extensions"

I think this refers to running xauth to set an MIT Magic Cookie value in ~/.Xauthority which is like an API token that prevents other users on the same system from just connecting to your forwarded X11 port on localhost and rickrolling (at best) your screen.

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Xlibre

Posted Jun 23, 2025 8:29 UTC (Mon) by cortana (subscriber, #24596) [Link]

The SECURITY extension allows certain clients to be marked as "untrusted" which prevents them from being able to spy on input events, take screenshots of other clients and so on.

Unfortunately many clients break completely under such restrictions. For many years, Debian patched OpenSSH to disable the use of the SECURITY extension by deafult. Nowadays I think the situation is a bit better but I've not used X11 forwarding for a long time so haven't verified.