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7.5.4. Customizing the /etc/hosts File
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
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
127.0.0.1 localhost
127.0.1.1 <FQDN> <HOSTNAME>
<192.168.1.1> <FQDN> <HOSTNAME> [alias1] [alias2 ...]
::1 localhost ip6-localhost ip6-loopback ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
# End /etc/hosts
EOF
cat > /etc/hosts << "EOF"
# Begin /etc/hosts
127.0.0.1 localhost
127.0.1.1 <FQDN> <HOSTNAME>
<192.168.1.1> <FQDN> <HOSTNAME> [alias1] [alias2 ...]
::1 localhost ip6-localhost ip6-loopback ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
# End /etc/hosts
EOF
The <192.168.1.1>, <FQDN>, and <HOSTNAME> values need to be changed for specific uses 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.