Allowing remote X sessions

A couple of posts before, I have described how to use gdmsetup to enable (in conjunction with xhost + command) remote X applications on your machine.

I've been working with our engineers (OK, here goes the mention - Dave Williams, who is fast becoming a Linux expert, and Martin Pain - who, similarly is becoming Oracle and SQL ex if not expert), to update our various course setup documents. The fix for gdmsetup needed to be scripted. A simple trick allowed me to identify the configuration line that needed to be changed:

First save the current setting in a different file:

# cp /etc/X11/gdm/gdm.conf /tmp/x.$$

Then change the setting; run:

# gdmsetup

Select Security tab, and modify the setting for the "Always disallow TCP connections...".

Once done, just compare the two files:

# diff /etc/X11/gdm/gdm.conf /tmp/x.$$
191c191
< disallowtcp="true
---
> DisallowTCP=false

Bobs your uncle. A single line (or two):

sed '/DisallowTCP/s/false/true/' /etc/X11/gdm/gdm.conf > /tmp/x$$
mv /tmp/x$$ /etc/X11/gdm/gdm.conf

placed in an appropriate script, and X applications will now be accepted.