Login as the root and type:
# ip route add default via 192.168.1.254
OR
$ sudo ip route add default via 192.168.1.254
route command to set a default router to 192.168.1.254
Login as the root and type:
# route add default gw 192.168.1.254
OR
$ sudo route add default gw 192.168.1.254
Save routing information to a configuration file /etc/network/interfaces
Open /etc/network/interfaces file
# vi /etc/network/interfaces
OR
$ sudo vi /etc/network/interfaces
Find eth0 or desired network interface and add following option
gateway 192.168.1.254
Save and close the file. Restart networking:
# /etc/init.d/networking restart
OR
$ sudo /etc/init.d/networking restart
Per i DNS, editare il file /etc/resolv.conf ed aggiungere:
nameserver 8.8.8.8
nameserver 8.8.4.4