[Techtalk] Shutting off X ports.

[Telsa Gwynne]

On Thu, Aug 28, 2003 at 07:20:23PM +0100 or thereabouts, Conor Daly wrote:
> On Wed, Aug 27, 2003 at 06:51:41AM -0700 or so it is rumoured hereabouts, 
> joe shindlin thought:
> > 
> > Starting nmap V. 2.54BETA34 ( www.insecure.org/nmap/ )
> > Interesting ports on localhost (127.0.0.1):
>                                   ^^^^^^^^^
> Note this is the loopback address: your machine's address for itself.

> > 6000/tcp   open        X11
> > Nmap run completed -- 1 IP address (1 host up) scanned
> > in 0 seconds
> 
> This seems to say that the listed ports are open to your own machine.
> This is fine since X uses network protocols within the machine as well as
> externally.  In fact, many *nix programs/services assume the existence of
> a network.  The loopback address exists to serve that assumption.

I remember a baffling set of symptoms which were once introduced to
us on IRC as "Gnome is broken". (And X. And a variety of other things.)
Eventually, we figured out what was wrong.  I have only ever seen this once. 

The guy was trying to be super-secure and didn't understand that
X used the network. 

He had firewalled himself from localhost.

Don't do this. Things break :) 

Telsa