Sharing an Internet connection

Router — configuration

The nice thing about routers is that there isn’t really much configuration. Once it’s plugged in and turned on, it’ll probably just work.

If it doesn’t, you should check to see if your Internet provider requires any login information. DSL companies, for example, often use PPPoE to authenticate their users. If you think this applies to you, look for a PPPoE user/pass section in your router’s control panel. Enter the appropriate information, and your service should work. Note that if you’re an AOL Broadband user, you need to find AOL login settings (currently available only in select Linksys routers).

Cable companies are more likely to use MAC authentication. This method depends on the fact that almost every network device has a unique 12-digit ID called a MAC address. When the cable technicians install your service, they bind it to the MAC address of your computer’s NIC. Subsequently, the cable company can deny Internet access if the cable modem is connected to any other device (in our case, a router).

There are two equally-functional ways to get around this. Both require you to know the MAC address of the offending NIC. To find out what it is, go to the Run box (Start » Run...). On Win9x, type "winipcfg"; on WinXP/2k, type “command” and enter "ipconfig /all" at the prompt. The field called Physical Address is your MAC address. Write it down, then…

  1. Call the cable company. The officially sanctioned way to get things done. It’s also a hassle. You call them. You tell them to change the MAC address on your account. They try to ask you why you’re changing it. Sometimes, they get really lonely and ask you for a date. It’s not pretty.
  2. Use MAC spoofing. You know how you [used to] lie about your age to impress the opposite sex? Well, most routers can lie about their MAC addresses, which fools the cable modem into thinking that it’s still talking to your computer’s NIC. Just visit your router control panel and look for the appropriate option. It’s easy and spoofalicious.

By now, you should have shared Internet access through the router. If not, the first step is to completely power off the cable/DSL modem and router for several minutes. This will clear out any old settings and IP leases.

If that doesn’t help, check the status page in your router control panel. If it’s not getting a valid IP (you’ll see or 192.168.x.x in the IP address field), the problem is probably outside your control. Call the cable company and complain. Avoid telling them about your router; if they know about it, they'll use it as an excuse to ignore you.

Alternatively, if you’re leasing an IP address successfully and your computers still can’t access the net, check your router’s DHCP settings. The DHCP server should be turned ON. Also, all of your computers should be set to obtain an IP address automatically. Since this is the default setting, it probably hasn’t changed unless you consciously modified it. To check, however, access your Network Properties (in Win9x, Start » Settings » Control Panel » Network; in WinXP, open Properties for Local Area Connection in your Network Connections folder). Then open the sub-properties for TCP/IP. The setting should be immediately visible.

If this tinkering gets it to work, congratulations! On the other hand, if it’s basically working but you've got problems with certain applications (especially games) or want to enhance security, proceed to the special applications page.