Use Remote Desktop for Computers Behind Routers
I repeatedly read about issues with Remote Desktop in the newsgroups. How do you use Remote Desktop over the Internet when there's router (often called a gateway) at the other end? The router performs Network Address Translation (NAT), which makes all of the PCs on your local network behind the router appear to have the same IP address, the address of the router.
Remote Desktop uses TCP port 3389 for its connection, so there are several pieces to the puzzle you need to configure.
1.
Enable Remote Desktop on the Remote Desktop host PC. See Set Up Your Computer for Remote Desktop and my earlier column on tuning Remote Desktop for slow links.
2.
If you're using Windows Firewall in Windows XP Service Pack 2 (SP2), it will be automatically configured when you turn on Remote Desktop. If you're using a third-party firewall, consult the documentation for that product to allow incoming traffic to TCP port 3389.
3.
Configure the router to forward traffic for TCP port 3389 to the IP address of the Remote Desktop host PC. This will be different on every version of router software, but all involve roughly the same steps.
This is how I configure my XiNCOM Dual WAN router:
1.
Log on to the router using the Internet Explorer interface.
2.
Enable a virtual server for Remote Desktop, as shown in Figure 1.
Figure 1
Figure 1
3.
Point the endpoint of the virtual server to the IP address of my PC.
4.
Determine the IP address of your router. This can be difficult if you don't have a fixed IP address and most people don't. However, many routers now support dynamic DNS services such as TZO.com and DynDNS.org, which let you use DNS to find your domain even when your address changes at the discretion of your ISP. If your router doesn't provide built-in support for dynamic DNS, most of the available services have client software that you can run on your PC to manage the process.
Figure 1
Figure 2
5.
On the client PC you want to connect with, open the Remote Desktop Connection Wizard shown in Figure 3 and enter the IP address or the DNS name of your router, not of your Remote Desktop host PC.
Figure 1
Figure 3
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Configure a Network with Multiple Routers
As more of us set up home networks with both wireless and wired devices, our networks become increasingly complicated. One question I've run into repeatedly in the newsgroups is how to configure and connect a wireless router (also known as a wireless gateway) when adding it to a network that uses a wired router.
The first answer, actually, is to not buy a wireless router if you already have a wired router—get a wireless access point (AP). They generally cost about the same as a router, but are specifically designed to do what you need. But for those of you who already have a router, here are some basic configuration steps.
1.
Ideally, only one router should act as a Dynamic Host Configuration Protocol (DHCP) server. You can choose which one, but generally it should be the one directly connected to the DSL/cable modem. Disable the DHCP server on the second router.
2.
Or you can carefully configure them both to act as DHCP servers, but use different address ranges of the same address prefix defined for the subnet. For example, I could configure the wired router to hand out DHCP addresses in the range from 192.168.0.50–192.168.0.99, while configuring the wireless router to serve out addresses in the 192.168.0.100–192.168.0.149 range, as shown in Figure 4. The catch here is that the default address range for the two routers may be different, especially if they came from different manufacturers. If they are, you'll need to change them so that they're both part of the address range being used on the home network subnet.
Figure 1
Figure 4
3.
Configure the second router to be a bridge, not a router. Not all routers will do this, however. Check the software for the two routers you have, and if only one of them can act as a bridge, set it up to do bridging and connect the other one to the cable/DSL modem. My D-Link wireless router won't act as a bridge, so I would have to connect it to the DSL modem.
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Why Automatically Configured Addresses Can Cause Problems
It's annoying when a computer that used to work properly suddenly stops connecting to other computers on the network and to the Internet. If the number of messages found on community forums is any indication, this happens all too often. It's more of a problem with wireless, but I've seen it with wired networks too. Although there can be several reasons why a particular computer suddenly stops connecting to other computers, one explanation has to do with automatically configured IP addresses.
In Windows XP, the default configuration is for your network connections to automatically obtain an IP address configuration.