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Remote Connection through the Router

When you're on the road and want to connect to your home PC with remote access software, how do you get through the router? Plus: Another look at why networks with routers don't need to use Windows Internet Connection Sharing.

By Joe and Ron of Neighborhood Techs

Q. I would like to be able to connect to my home PC from a remote location. The PC is behind a Linksys firewall/router. I can connect to the router remotely, but not to the PC beyond it. Do you have any ideas about how to do this?

A. Yes, it should be possible to remotely access your PC through a router, but it will require a little bit of configuration on your part.

By default, most routers are configured to allow incoming traffic from the WAN interface only when it is in response to a session that originated on your internal LAN. As a security measure, any unsolicited incoming traffic is dropped.

What you'll need to do is modify this default behavior. You didn't say what specific model of Linksys router you have, but most can be set to allow certain types of traffic to come into the router on the WAN port and make its way to a machine on your LAN.

This feature is called port forwarding, and you typically need it for anything that requires access to your LAN from the outside, like running a Web or FTP server, online gaming, and of course, remote access.

You mentioned that you were already able to access the router remotely. Others may need to enable this feature as well, since most routers don't do it by default. You may also have needed to specify a specific port to use for access. This way, when you type in your router's IP address and port (i.e. http://10.0.0.1:2048 where 10.0.0.1 is the IP and 2048 is the port number) the router knows to respond to the request and prompt you for authentication.

To remotely access your PC in the same manner, enable and configure the port forwarding feature on your router. Different remote access programs such as PCAnyWhere or GoToMyPC use different ports, so you'll need to check your program's documentation to determine which port (or more likely, ports) you'll need to open. In some cases, you'll need to use one or more individual ports, and in others it may be a range of ports.

In either case, the next step is to find the port forwarding configuration screen on your router (remember, not all routers support this feature). Enter the ports that you need to use in the spaces provided, along with the IP address of the PC in question. Incidentally, you'll probably want to make sure that any PC you want remote access to is using a static IP address. If you use DCHP to assign an address to your PC, the address could later change. If this happens, the router will be forwarding to the wrong address, and you won't be able to remotely access your computer.  

After you have the router passing the appropriate traffic through to the PC you want to control, it will be able to respond you requests and you shouldn't have any problems.

Please be sure to enable any security features your remote access software provides and set up a strong password. A strong password would be one at least eight characters in length, in mixed case, with numbers as well as letters, and maybe some punctuation marks, too. Once those ports are open, a strong password may be all that stands in the way of someone with dishonorable intentions getting access to your computer.

Q. My roommate and I are having problems trying to share an Internet connection. My roommate has an ADSL modem and a Windows XP Professional computer set up as the host. We bought a D-Link DI-604 router and connected the network cable from the DSL modem to the WAN port, then connected both of our computers to LAN ports on the router. We both have Windows XP; she has Professional, and I have Home Edition.

After we connect everything, we try to use the Network Setup Wizard and get an error message that says, "Cannot complete the Network setup wizard: Other computers cannot connect to the Internet through this computer. In addition to its Internet connection, this computer must have a connection to your network."

A. If you have a broadband router like the DI-604, then you don't need the Internet Connection Sharing (ICS) feature in Windows XP. ICS is necessary only when you lack a router, and instead connect your Internet connection directly to a PC. You then need a separate network card in that host PC to connect to your internal network and the machines on it, which allows that connection to be shared. You don't have that setup with a router, thus you got the error message.

You simply connected the computers to the router and then the router to the DSL without doing any kind of configuration on any of the devices. You've got the physical connections right, but that's only half of the equation.

Here's what you need to do. Make sure both computers are set to "Obtain an IP address automatically." This will allow them to obtain an address from the router using DHCP when you connect them to it. You might need to reboot the machines to get an address issued.

Then, connect to the router via a Web browser, using the default address and logon information provided in the documentation (it's probably 192.168.0.1 or something similar -- type that into your browser). Most of today's routers come with a setup wizard of their own, and you'll want to start there. This will configure the router to work with the type of broadband connection you have.

Once this is done, you should find that both of your computers now have access to that shared Internet connection.

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