auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
  address 10.4.1.169
  netmask 255.255.252.0
  gateway 10.4.0.1

auto eth0:0
iface eth0:0 inet static
  address 10.4.1.170
  netmask 255.255.252.0
  gateway 10.4.0.1