someone added a bunch of iface statements for configuration but forgot the auto part…

# sed -i 's/iface eth0:\([0-9]\{3\}\)/auto eth0:\1\niface eth0:\1/' /etc/network/interfaces

<snip>
auto eth0:196
iface eth0:196 inet static
  address 1.2.3.4
  netmask 255.255.255.0
auto eth0:197
iface eth0:197 inet static
  address 1.2.3.5
  netmask 255.255.255.0
auto eth0:198
iface eth0:198 inet static
  address 1.2.3.6
  netmask 255.255.255.0
</snip>