Objectives

In this chapter, we will look at how to connect our systems to an “external” network—in this case, the Internet. We'll see how to add routes to the systems to make sure they can all connect to the external machines.

We saw earlier in Chapter 11, “Connecting to the Local Area Network,” how to configure systems for a local network. The next task is to extend this and connect them to another, wider, network.

Many companies now have a permanent connection to an external network; that is, something other than the LAN. This may be, for example, a remote part of the company network, or a connection to an Internet Service Provider (ISP), which in turn allows them to connect to the Internet. In simple terms these are all “internets” (i.e., networks of computers connected together by routers), and it is the method of connection we will describe here.

Although we are using a permanent network connection here, the basic theory and settings will also apply if you are using a modem—we'll discuss this method of connectivity in Chapter 15, “Dialing in with PPP.” In general, the main tasks that we need to carry out here are very similar to a local connection, and are as follows:

• Assign a name and IP address to an additional network interface.
  
  
• Add any required routes.
  
  
• Configure resolving.
  
  
• Check that the interface is working correctly.