Initial /etc/inet/hosts File

When you run the Solaris installation program on a machine, the program configures the initial /etc/inet/hosts file. This file contains the minimum entries that the local host requires. The entries include the loopback address, the host IPv4 address, and the host name.

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

Example 5–1 /etc/inet/hosts File for Machine ahaggar

127.0.0.1     localhost         loghost    #loopback address
192.9.200.3   tenere                      #host name

Loopback Address

In Example 5–1, the IPv4 address 127.0.0.1 is the loopback address. The loopback address is the reserved network interface that is used by the local machine to allow interprocess communication. This enables the host to send 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 IPv4 address 192.9.200.1 and the name tenere 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, because they are either routers or multihomed hosts. Each additional network interface that is attached to the machine requires its own IPv4 address and associated name. When you configure a router or multihomed host, you must add this information manually to the router's /etc/inet/hosts file. See Configuring Routers for more information on configuring routers and multihomed hosts.

Example 5–2 is the /etc/inet/hosts file for machine timbuktu that is shown in Figure 4–1.

Example 5–2 /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.