The system's networking configuration is contained within several files in the /etc directory. Together these files specify hostname, IP address and mask, routing, DNS resolution and firewall configuration.
/etc/hostname -- Enter the fully-qualified domain name of the machine.
hal9000.discovery.lan
/etc/interfaces -- Enter the interface name, IP address and network mask.
eth0 192.168.1.5 netmask 255.255.255.0
/etc/routes
/etc/resolv.conf
/etc/firewall