PPTP and remote X apps
 

Hi all,

Here's my situation. I am trying to make a VPN connection to my workplace via PPTP client on Linux. Right now I have the PPTP client working; that is, I am able to successfully make a connection to the VPN server at work, and device ppp0 is up and running correctly. I also added a route following the instructions on the PPTP howto, and can ping and telnet/ssh the machines in my workplace LAN.

So I thought everything was good and so I tried to launch X apps, such as gvim and xclock. I perform the following:

xhost + server.work.domain
telnet server.work.domain
setenv DISPLAY mycomputer:0

where server.work.domain is the address of the machine I wish to run the X apps from and mycomputer is the IP address assigned to me by the VPN server.

I then type 'xclock' and NOTHING pops up!! Strangely though, I don't get any error messages either (ie. no "Can't open display") or any error messages of that sort. It seems as though everything is working except I don't see the clock on my screen!

Trying to debug the issue, I try the exact same procedure on my Windows machine. In WinXP I successfully connect to the workplace LAN using VPN, and start Exceed as my X server. I telnet to server.work.domain through DOS prompt, set the display accordingly, and run 'xclock'. Instantly Exceed asks if I want to allow the incoming X client request, I click 'OK" and it works!! So X apps run fine in Windows but not Linux, argh......frustrating!!

Does anyone have any ideas?? I don't know if it could be a router issue as well, as both computers at home are behind a DLink router. However, I did not change any router settings, so WinXP bascially works out of the box and Linux for some reason won't display my remote X apps, even though it seems as though it's working.

Thanks for the help!

Oh yeah I should mention that I use Debian, using XFCE4 as windows manager.

And despite the fact everything works in WinXP, I would really like to get things working in Debian because that's the computer sitting on my desk. My WinXP machine is being used as a PVR box and is connected to my TV :)

I solved this problem!!! It turned out to be the MTU issue with ppp0. For all those people who encounter the bizzare problem that I had, try setting your MTU for ppp0 lower, to say like 400. My default of 1496 didn't work, giving me headaches until I turned the MTU down, and everything WORKED! You can do this temporarily by doing 'ifconfig mtu xxx ppp0'.

Thank you to Vincent Zweije (author of "Remote X apps mini How-To") for his insight into the problem, it was he who suggested lowering my MTU value. I give him all the credit :)