iface eno1 inet static
address 1.2.3.4
netmask 255.255.255.0
gateway 1.2.3.1
up route add -net 1.2.3.4 netmask 255.255.255.0 gw 1.2.3.1 eno1
up ip addr add 4.3.2.1/32 dev eno1
down ip addr add 4.3.2.1/32 dev eno1