SNAT: add device to rules even with (old-style) virtual interfaces

[Adi Kriegisch]

I'm using old-style virtual interfaces (eth0:0, ...). An interface definition looks like this (interface is named GW):

ACTIVE="Yes"
IPADDRESS="10.10.10.1"
DEVICE="eth0:1"
VIRTUAL="Yes"
(...)

When I use this interface for SNAT

Snat service any from my.lan to world.inet options out_int=\"GW\"

the iptables rules created omit the "-o eth0" part which causes me troubles because I have several other outgoing interfaces and all pakets originating from 'my.lan' end up being SNATed to GW's ip.

The interfaces were created with 'ip':

ip addr add 10.10.10.1 brd 10.10.10.255 dev eth0 label eth0:1

From ip-address man page:

       label NAME
              Each address may be tagged with a label string.  In order to
              preserve compatibility with Linux-2.0 net aliases, this string
              must coincide with the name of the device or must be prefixed
              with the device name followed by colon.

So assuming if there is a colon in the interface name, the part up to the first colon is the physical device's name seems sane and may be used for the '-o' option...