Configuring a Router or Residential Gateway
Connecting a router to your network isn't a particularly difficult task. First plug your cable or DSL modem into the WAN port on the router; then plug the hub or switch that connects computers on your local network into the LAN port on the router. (If your router includes an integrated hub or switch, you can plug computers on your network directly into the LAN ports on the router.)

Most routers include a configuration utility, typically accessed through a Web-based interface. With the popular Linksys BEFSR41 and BEFSR81 routers, for instance, you load the configuration page shown in Figure 15-5 by typing the URL http://192.168.1.1 and entering the default password, admin.


Figure 15-5. Most routers, like this Linksys model, use a Web-based configuration utility.
The first step is to establish your Internet connection. If you normally acquire an IP address automatically through DHCP, choose this option for your router. Depending on your ISP, you might need to supply a fixed IP address, enter the addresses of DNS servers, or both. You might also have to perform additional steps, such as setting up a PPP Over Ethernet (PPPoE) logon for the router or changing the MAC (media access control) address of your router so that it matches the MAC address of your primary computer.

Troubleshooting
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You can't connect to the configuration page for your router

When setting up a router, you need to supply its IP address, typically by typing it into the Address bar of Internet Explorer. If your computer and the router have IP addresses on different subnets, you'll be unable to connect. Your computer should acquire an IP address automatically from the DHCP server on the router. This option will fail if the router's DHCP capabilities have been previously disabled, or if another DHCP server is running elsewhere on the network. Try any of these strategies to solve the problem:

Disconnect all other computers from the network, leaving only the LAN connection for your computer and the WAN connection enabled. Make sure your computer is set to acquire an IP address automatically and try again.
Operate the router's reset switch to apply the default settings. This should enable the DHCP capabilities again.
If all else fails, assign a temporary static IP address to your computer. Make sure this address is on the same subnet as the router, and specify the router's IP address as the gateway. For instance, if the router's address is 192.168.1.1, assign your computer the address 192.168.1.2, with a subnet mask of 255.255.255.0 and a gateway of 192.168.1.1.
Next set up the router's internal DHCP server. When this feature is enabled, the router responds to requests for an IP address from computers on your local network. You can typically specify a range of private IP addresses. Depending on the router, you may be able to map specific IP addresses to specific MAC addresses so that each computer on your network always receives the same IP address when connecting to the network.

Finally, close the configuration utility and configure each computer on the network to acquire an IP address automatically. (For computers running Windows XP, you should use the Network Setup Wizard for this task.) After confirming that the router is doing its job, you can set up advanced features, such as packet filtering and port forwarding.

INSIDEOUT
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Bypass ISP restrictions on servers

Some routers allow you to create virtual servers inside your network, passing specific ports through the router to a designated IP address. This capability can be a useful (but potentially dangerous) way to get around the blocks that many Internet service providers place on Web and FTP servers. You might want to run a personal Web server on which you can share photos with other family members, but access from the outside will fail if your ISP blocks port 80, the standard port used by Web servers. The solution is to configure the Web server to use a port that isn't blocked, such as 8080, and then use the router's port-forwarding features to pass all outside traffic on port 8080 directly to the IP address of the computer running the Web server. Anyone making a connection to the server will need to specify the public IP address of the router, followed by a colon and the port number. If you choose this option, be certain that you update the Web server software regularly with the latest security patches. And don't try to use this "under the radar" capability for a high-volume Web site unless you're prepared for a confrontation with your ISP.

Libellés : Configuring, Gateway, Residential, Router