#875721 sddm: auth file passed to Xserver doesn't allow tcp connections

Package:
sddm
Source:
sddm
Description:
modern display manager for X11
Submitter:
Bruce Robson
Date:
2026-10-13 02:49:05 UTC
Severity:
important
#875721#5
Date:
2017-09-14 00:17:38 UTC
From:
To:
Dear Maintainer,

I'm running testing (buster) on one of my PCs. This uses sddm instead of the
previous kdm.

kdm generates an auth file for passing to the Xserver that uses the
wildcard value for connection method. e.g.
    #ffff##:  MIT-MAGIC-COOKIE-1  68389d0b79e85041a85532b41264b110

sddm instead generates an auth file for passing to the XServer that uses the
computer hostname and unix connection method. e.g.
    hostname/unix:0  MIT-MAGIC-COOKIE-1  68389d0b79e85041a85532b41264b110
This is true even after I have created a /etc/sddm.conf file with the line
    ServerArguments=-listen tcp
to enable tcp connections to the Xserver.

Because of this change to the Xserver auth file it is not possible with sddm
to authorise tcp connections to the Xserver using MIT-MAGIC-COOKIE-1 entries
in the .XAuthority file on a remote computer.
#875721#10
Date:
2026-10-13 02:48:12 UTC
From:
To:
Version: 0.20.0-1


Upstream commit cb5c07b4c5bafa27b21981a8f4039eadbe0fafdf
rewrote Xauthority handling using libXau. XAuth::writeCookieToFile() writes the same cookie
as both FamilyLocal and FamilyWild, including the authentication file passed to the Xserver by
XorgDisplayServer. This addresses the missing wildcard-family entry described in this report.

The fix is included in upstream 0.20.0 and Debian 0.20.0-1. Closing with
that historical fixed version. TCP listening still requires explicit configuration.

Regards,
Boyuan Yang