Quiet X on Port 6000 TCP

Page 260 of the second edition of Hacking Linux Exposed gives a simple trick to prevent X from listening on port 6000. If you run the X Window System using 'startx' from the command prompt, and have nothing but sshd listening, you'll find port 6000 listening once X starts:

netstat -natup



Active Internet connections (servers and established)

Proto Recv-Q Send-Q Local Address           Foreign Address         State

tcp        0      0 0.0.0.0:6000            0.0.0.0:*               LISTEN             

tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN

Instead launch the X server using 'startx -- -nolisten tcp'. Here's the netstat output now:

Active Internet connections (servers and established)

Proto Recv-Q Send-Q Local Address           Foreign Address         State

tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN

Better yet, add the following to your .bash_profile to automate this process:

alias startx='startx -- -nolisten tcp'