single linux box on dsl?

Tom 'Needs A Hat' Mitchell mitch48 at
Fri May 14 22:17:41 UTC 2004

On Fri, May 14, 2004 at 03:38:58PM -0400, Jeremy Brown wrote:
> Tom 'Needs A Hat' Mitchell wrote:
> >On Thu, May 13, 2004 at 10:32:27AM -0400, Jay Daniels wrote:
> > 
> >Not really.  X-Windows uses networking.
> >
> >However X is happy to use only the 127.0.0 localhost (loopback)
> >network and does not need to connect to or accept connections 
> >from networks to the outside world.
> > 
> >
> Not to nitpick, but we just had a thread about this.  X11 mostly uses 
> UNIX domain sockets for local communication (file-based, they reside in 
> "/tmp" if you're curious).  TCP-based communication (i.e. "using ports") 
> is disabled by default in Fedora.

Nitpicking is good.
I learned some stuff in this discussion.

When the client is using DISPLAY set thus:
  $ echo $DISPLAY
I see "socket(PF_UNIX, SOCK_STREAM, 0)" in the system call trace of a
client.  (PF_UNIX, PF_LOCAL Local communication)

and when the client is using DISPLAY set thus:
   $ echo $DISPLAY
I see "socket(PF_INET, SOCK_STREAM, IPPROTO_IP)" in the system call
trace of a client (PF_INET IPv4 Internet protocols).  And this does fail
unless I tell 

and when I ssh in I see  DISPLAY set thus:
   $ echo $DISPLAY
I see "socket(PF_INET, SOCK_STREAM, IPPROTO_IP)"....

So I stand corrected -- while all the communications are
done with sockets local communication need not use
TCP any more.

By tinkering with /etc/X11/gdm/gdm.confn
   $ diff gdm*
   > DisallowTCP=false

remote access ports will be opened by gdm that can then in turn be
blocked by packet/port filters.  Other window managers (there are
lots) may act or be configured differently.

	T o m  M i t c h e l l 
	/dev/null the ultimate in secure storage.

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