Resolving X display through Linksys Router

[Denton Williams]

Hi All,
I am trying to resolve X display behind a Linksys firewall. I have a couple of HP-UX 11 servers and will on both sides of the firewall and will like to resolve X displays. Can someone please help me in figuring out how I could do it. The Linksys folks where unable to help.

Thanks,
Dee.

[Bill Hassell]

There is no way to resolve your Xdisplay address because your local IP address is probably 192.168.1.something, like several thousand other computers. It doesn't matter if it is a Linksys or D-Link or whatever, your local computer does not have a public IP address. To set this up, you first have to ask your ISP to give your Linksys a fixed IP address (this will usually cost you $10-20 per month) then you'll have to setup your Linksys to pass certain port numbers through to your local computer.

NOTE: Xwindows a a very bad protocol to use over the open Internet. Once hackers discover your fixed IP address, they will discover port 6000 and start trying to display windows on your screen. You can circumvent some of this by using SSH on your HP-UX box and setting up an Xwindow tunnel, but I would still be concerned about opening ports like this without some serious firewall protection.

[Ron Kinner]

If you are talking about one of the Linksys routers with the builtin 4 port switch I believe the Linksys has an option to put up a server on a static address and open certain ports to it. It doesn't matter that it will have a 192.168.1 address since the router will do NAT and hide it. What happens is that all traffic to a particular port (I presume Bill is correct that 6000 is the correct port) will be automatically routed to a particular IP address on your internal network. I'm not sure that it will allow more than one tho but if it did you would need to tell X to use a different port on the second server since you only have the one valid address. Would have to reread the instruction manual for that and you didn't give the part number of the Linksys.

As Bill says this is probably not the smartest thing to do unless the Linksys is able to filter and only allow certain designated good guys through to your server. Again I need to read the manual to be sure.


Ron

[Bill Hassell]

The X11 ports are 6000-6063. When I mentioned a fixed IP address, I wasn't clear. The Linksys will indeed use NAT to hide the 192 address. However, in your router, you must tell it that all traffic for ports 6000-6063 should be sent to your local HP-UX box. To make this stable, the HP-UX box should use a fixed IP address, not DHCP on your local network, perhaps 192.168.0.100 or something similar.

However, your ISP normally supplies the Linksys router with a DHCP address so telling the remote system where you are must be done for each connection--or get the ISP to assign your router a fixed address (usually costs extra money).