Hi,

rdnssd modifies the permissions + ownership of /var/run/rdnssd on
each and every single service startup.

This is caused by /usr/lib/systemd/system/rdnssd.service with:

  ExecStartPre=/bin/mkdir -p /var/run/rdnssd
  ExecStartPre=/bin/chown rdnssd:nogroup /var/run/rdnssd
  ExecStartPre=/bin/chmod 0755 /var/run/rdnssd

While this admittedly is just a runtime directory, it still causes
possibly unnecessary executions, and overrides any local permissions
and ownership changes possibly done by the local user.

If at all, such a change should be implemented in maintainer scripts
if relevant for upgrades, or (otherwise and preferably) in a
declarative way via systemd's tmpfiles.d(5).

BTW: /var/run is also deprecated and should be /run instead those
days, see
https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch05s13.html +
https://wiki.debian.org/ReleaseGoals/RunDirectory

regards
-mika-