Those options are no longer supported in GDM. I think that they were removed with GDM 2.24 (at the latest, probably 2.22) and C6 is running GDM 2.30.
That is unfortunate... I suppose I will just have to ignore this issue then.
in "/etc/gdm/custom.conf" to override the "-nolisten tcp" but I have no idea about "-br -audit 4 -s 15".
Thanks for your help. I really wish someone know where I could edit those parameters.
Regards,
Stephen Jamieson