Comment 5 for bug 498434

Found the gdm daemon to be documented in /usr/share/gnome/help-langpack/gdm/en_GB/gdm.xml although I am:
1) Unsure how a user should find this information (simplest way to access this in readable format)
2) Unsure if this works (needs testing)
3) Surprised not to see this documented elsewhere (wiki)

Below is the section this bug is concerned with. Attached is a simplified text file of the configuration options found in the xml file cited above.

Config file:
/etc/gdm/custom.conf

Security Options
[security]

Option:
DisallowTCP

Usage example:
DisallowTCP=true

Details:
If true, then always append -nolisten tcp to the command line when starting attached Xservers, thus disallowing TCP connection. This is a more secure configuration if you are not using remote connections.