X Windows and VPN

I've got a PPTP tunnel working between my Linux machine and the
Windows 2K servers at work. Once the tunnel is set up I can then
telnet into the HP UX machines (where I live) with no problems.

The problem is that if I want to start an xterm or any other X based
application. I get a message that the app can't find the display. I'm
specifing (via the -display option) the local IP that is assigned
when PPTP sets up the tunnel. I can telnet into my own machine from the
remote machine using that same IP.

I don't get it. Can someone tell me what's going on with this?

Thanks,

James Kimble

James Kimble wrote:

> I've got a PPTP tunnel working between my Linux machine and the
> Windows 2K servers at work. Once the tunnel is set up I can then
> telnet into the HP UX machines (where I live) with no problems.
>
> The problem is that if I want to start an xterm or any other X based
> application. I get a message that the app can't find the display. I'm
> specifing (via the -display option) the local IP that is assigned
> when PPTP sets up the tunnel. I can telnet into my own machine from the
> remote machine using that same IP.
>
> I don't get it. Can someone tell me what's going on with this?
>
> Thanks,
>
> James Kimble

A very simple check - have you used on the maachine you want to display on
xhost +<other machine name> first?

Yes, I did do that. I even tried just "xhost +" to make sure I wasn't
using the wrong IP. No diff.



>
> A very simple check - have you used on the maachine you want to display on
> xhost +<other machine name> first?

James Kimble wrote:

> Yes, I did do that. I even tried just "xhost +" to make sure I wasn't
> using the wrong IP. No diff.
>
>
>
>>
>> A very simple check - have you used on the maachine you want to display
>> on xhost +<other machine name> first?

You'll need to check the simple setup, then.

Can you display locally?

E.g. log in under X, run

xhost +localhost

then log in as another user, and open an X application.

If that works, then try it again, but use the network IP addy of the machine
you are on, rather than localhost.

On the remote machine, try using telnet:

telnet <machine name> 6000

(there are several X11 reserved IP addresses, check /etc/services for lines
beginning with x11).

if telnet is refused all of them, then make sure you are disconnected from
the internet and turn off the firewall on both systems (iptables -F). Go
through the steps above.

You're basically trying to cut off the reasons for failure one by one.

Ta.

Try disabling any firewall you may have configured as a test. The
"backlink" from the X server (host) appears to the client machine as
an incoming connection rather than a response. Most desktop firewalls
assume that such traffic is not valid unless it has been explicitly
enabled.