Remote Desktop

[TC2]

I'm trying to help a very small business access a computer across the net. I
can use Remote Desktop within the LAN. It's a peer-to-peer XP Pro network on
a Linksys BEFSR11 router and a cable modem. The inexpensive one you can find
in most retail shops. They don't have their own IP range. They can get a
static IP from their ISP. (For now for experimenting I can just get the
dynamic IP the router got assigne dby the ISP.) I can make a system in house
exposed to the internet or do some other method? But how do I find that
particular system acorss the net? Since they don't own their own IP range if
I just use one of the addresses in the router's range I'll probably end up
being redundant with other systems out there.

Thanks,
Tom

 

[Bruce J. Weiers]

Let's call the computer, which you will want to access across the
internet, the "desktop".

When you access the "desktop", you will be using the IP address assigned
by the cable modem, that is the WAN IP address of the Linksys.

When the Linksys receives the remote desktop request from across the
internet, it will forward it to the Windows XP "desktop."

Remote desktop communications ordinarily happen on Port 3389. So the
Linksys will have to be told to forward TCP and UDP communications on
Port 3389 to the specific local IP address of the "desktop". The
Linksys interface should provide an obvious place to this; if the
Linksys is a couple of years old, you may need to update the firmware;
the earliest versions of the router did not really have the ability to
properly forward ports, and this was corrected with updated firmware.

You probably should assign a static address to the "desktop" so that
these forwarding instructions are not screwed up by the Linksys's DHCP
service.

If you enable a firewall, even XP's own firewall, on the "desktop" you
will have to make an exception for remote desktop.

(Some cable systems may not permit communications on Port 3389; it has
been known to happen.)

 

[TC2]

Excellent description of how to do that. But it didn't work. I can query the
router for the IP it got from the ISP. I can ping that address from within
the network, which I assume must go outside and come back since it's not in
the in-house range. But from an outside computer a ping or attempt to
connect by Remote Desktop fails. The router has an option to block WAN
requests. I turned that off. Maybe I'm real close and there's some little
thing I'm missingm, or maybe I just can't get there from here without
setting up a VPN or using pcAnywhere or something.

Thanks,
Tom

 

[Bruce J. Weiers]

Are you saying you cannot ping the router, using the ISP-assigned IP
from outside your private LAN?

Most home routers allow you to assign one computer to the "DMZ", which
means that that one computer is exposed to the internet, exactly as if
it had the ISP-assigned public IP address. I don't know if the Linksys
has that feature, but it would simplify things.

(I hope you updated the Linksys firmware. I had a very frustrating
afternoon, once a couple of years ago, with a Linksys, which had the
user interface to forward ports, but not the actual capability.)

As I mentioned, some cable companies simply don't let you communicate on
certain port ranges. There is a way to do remote desktop thru a webpage
interface, thus using Port 80, which is the port for web communications.
You might go to the work_remotely newsgroup and ask about that.

PCanywhere basically works the same way as Remote Desktop, though it
uses a different set of ports (21?).