Initial /etc/inet/hosts File

When you run the Solaris installation program on a machine, it sets up the initial /etc/inet/hosts file. This file contains the minimum entries that the local host requires: its loopback address, its IP address, and its host name.

For example, the Solaris installation program might create the following /etc/inet/hosts file for machine ahaggar shown in Figure 4-1:

Example 4-1 /etc/inet/hosts File for Machine ahaggar

127.0.0.1     localhost         loghost    #loopback address
192.9.200.3   ahaggar                      #host name

Loopback Address

In Example 4-1, the IP address 127.0.0.1 is the loopback address, the reserved network interface used by the local machine to allow interprocess communication so that it sends packets to itself. The ifconfig command uses the loopback address for configuration and testing, as explained in "ifconfig Command". Every machine on a TCP/IP network must use the IP address 127.0.0.1 for the local host.

Host Name

The IP address 192.9.200.3 and the name ahaggar are the address and host name of the local machine. They are assigned to the machine's primary network interface.

Multiple Network Interfaces

Some machines have more than one network interface, either because they are routers or multihomed hosts. Each additional network interface attached to the machine requires its own IP address and associated name. When you configure a router or multihomed host, you must manually add this information to the router's /etc/inet/hosts file. (See Chapter 5, Configuring Routers, for more information on setting up routers and multihomed hosts.)

Example 4-2 is the /etc/inet/hosts file for machine timbuktu shown in Figure 4-1.

Example 4-2 /etc/inet/hosts File for Machine timbuktu

127.0.0.1      localhost     loghost
192.9.200.70   timbuktu      #This is the local host name
192.9.201.10   timbuktu-201	#Interface to network 192.9.201

With these two interfaces, timbuktu connects networks 192.9.200 and 192.9.201 as a router.