Firewall Problems

If you have installed a router/switch device between your network and a broadband Internet connection, be sure to read the manual thoroughly and understand how the device should be configured. Many come with default settings, but you need to fill in some information, such as the address of the broadband link, if your service provider gives you a static address. In most cases, the provider will be using DHCP also, so you won't have to make any changes. If you do have to make changes, write them down and keep the information handy for later troubleshooting efforts.

Earlier in this chapter, you read that it's not a good idea to mix computers you use for play with those you use for business on the same network. If you do, you are just asking for trouble. If you play Internet games ”those that allow you to interact with other users playing the same game on the Internet ”you might be instructed to change the port settings on a small switch/router that also functions as a firewall. If you start playing around with opening, disabling, or forwarding ports, keep track of the changes you make. If something stops working after you've made a change, undo the modification and see whether the changes you've made have caused the problem.

Remember that the firewall capabilities of a small switch/router are minimal and are designed to protect you from simple attacks from the Internet. It might be that the default settings are very stringent, and if you end up making changes that relax the firewall settings, you might also be opening a door that can allow bad things into your small LAN.

For more information about how firewalls work and the features that are important, see Chapter 49, "Firewalls."