X forwarding

[Duane Attaway]

On Sat, 19 Oct 2002, Brad Crotchett wrote:

> 1. Does X have to be installed on a server in order to forward X
> clients?

The X applications you wish to display on your workstation will need X 
libraries on the box from which the processes are actually run.  This 
would include any library that app is linked to.  You can check to see 
which libraries, say xclock runs, with:

dattaway at satellite dattaway $ ldd /usr/X11R6/bin/xclock 
 libXaw.so.7 => /usr/X11R6/lib/libXaw.so.7 (0x40022000)
 libXmu.so.6 => /usr/X11R6/lib/libXmu.so.6 (0x4007f000)
 libXt.so.6 => /usr/X11R6/lib/libXt.so.6 (0x40095000)
 libSM.so.6 => /usr/X11R6/lib/libSM.so.6 (0x400e7000)
 libICE.so.6 => /usr/X11R6/lib/libICE.so.6 (0x400f1000)
 libXpm.so.4 => /usr/X11R6/lib/libXpm.so.4 (0x40109000)
 libXext.so.6 => /usr/X11R6/lib/libXext.so.6 (0x40119000)
 libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x40129000)
 libc.so.6 => /lib/libc.so.6 (0x401f1000)
 libdl.so.2 => /lib/libdl.so.2 (0x40320000)
 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

> 2. Does X have to be running on the server in order to forward X
> clients?

No.  But technically, your X server is your workstation and your X client 
is from your server.  Make sense?

> 3. What does it take to forward an entire X session so I can have a
> remote X session (workstation to workstation)?  Obviously X must be
> installed on the remote box.  Does it have to be running?  What is the
> best way to set that up?

You wish to have an X server forwarded to another X server?  Interesting.  
I usually export X clients to the X server (workstation, heh...) one by 
one...

> I have worked a bit with forwarding X clients through SSH and had mixed
> luck.  I am not sure what the factor is that causes it to fail
> sometimes.

How does it fail?

> 4.  Is it a security risk to run a remote X session to a server?  Can it be
> tunneled?  I am running an iptables firewall that is masquerading my home
> network.  Is there a viable VPN solution?

If you use the -X option with ssh to forward X11 packets, they should be 
encrypted.  Otherwise, those X11 widgets will be broadcasted in full glory 
over the wire (or wireless...)