If a network card is to be configured, decide on the IP address, fully-qualified domain name (FQDN), and possible aliases for use in the /etc/hosts file. The syntax is:
IP_address myhost.example.org aliases
Unless the computer is to be visible to the Internet (i.e., there is a registered domain and a valid block of assigned IP addresses—most users do not have this), make sure that the IP address is in the private network IP address range. Valid ranges are:
Private Network Address Range Normal Prefix 10.0.0.1 - 10.255.255.254 8 172.x.0.1 - 172.x.255.254 16 192.168.y.1 - 192.168.y.254 24
x can be any number in the range 16-31. y can be any number in the range 0-255.
A valid private IP address could be 192.168.1.1. A valid FQDN for this IP could be lfs.example.org.
Even if not using a network card, a valid FQDN is still required. This is necessary for certain programs to operate correctly.
Create the /etc/hosts file by running:
cat > /etc/hosts << "EOF" # Begin /etc/hosts (network card version) 127.0.0.1 localhost <192.168.1.1> <HOSTNAME.example.org> [alias1] [alias2 ...] # End /etc/hosts (network card version) EOF
The <192.168.1.1> and <HOSTNAME.example.org> values need to be changed for specific users or requirements (if assigned an IP address by a network/system administrator and the machine will be connected to an existing network). The optional alias name(s) can be omitted.
If a network card is not going to be configured, create the /etc/hosts file by running:
cat > /etc/hosts << "EOF" # Begin /etc/hosts (no network card version) 127.0.0.1 <HOSTNAME.example.org> <HOSTNAME> localhost # End /etc/hosts (no network card version) EOF