Ubuntu interfaces file examples
Example 1 - Includes some static routes and manually specified IP's
auto lo iface lo inet static address 103.90.59.9/32 auto ens3 iface ens3 inet static address 172.2.1.17 network 172.2.1.0 netmask 255.255.254.0 up route add -net 172.2.0.0 netmask 255.255.0.0 gw 172.2.1.1 up route add -net 172.2.0.0 netmask 255.255.0.0 gw 172.2.1.1 iface ens3 inet6 static address 2405:cc:ee:110::7 netmask 64 autoconf 0 accept_ra 0 gateway 2405:cc:ee:110:ff:ff auto ens4 iface ens4 inet static address 172.23.2.12 network 172.23.2.0 netmask 255.255.255.0 gateway 172.23.2.254 source /etc/network/interfaces.d/*.cfg