rutas

$ ip route show

# ip route add 10.8.0.0/24 via 192.168.1.50 dev eth0

/etc/network/interfaces

allow-hotplug eth0
iface eth0 inet static
  address 192.168.1.4        # este es mi caso
  netmask 255.255.255.0
  network 192.168.1.0
  broadcast 192.168.1.255
  gateway 192.168.1.1
 
### static routing ###
# añade una ruta a la red 10.0.0.0/8 a través del Gateway 10.9.38.65
  post-up route add -net 10.0.0.0 netmask 255.0.0.0 gw 10.9.38.65
  pre-down route del -net 10.0.0.0 netmask 255.0.0.0 gw 10.9.38.65

• https://www.cyberciti.biz/tips/configuring-static-routes-in-debian-or-red-hat-linux-systems.html