mark value as routing key

[Patrick McHardy]

Marco Berizzi wrote:
> Hi.
> 
> I have a problem with iptables mark target.
> I'm using iptables to mark packet in this manner:
> 
> iptables -t mangle -I OUTPUT --protocol tcp --dport 80 -j MARK --set-mark 1
> 
> This linux box has two different ip addresses on
> two different subnet on the same ethernet NIC:
> 
> eth0: 1.1.1.254/24
> eth0:adslA: 10.10.10.6/29
> 
> This is my ip rule sh output:
> 
> 0: from all lookup local
> 400: from all fwmark 0x1 lookup adsl
> 450: from all lookup hdsl
> 32766: from all lookup main
> 32767: from all lookup default
> 
> Here is ip route sh table adsl:
> default via 10.10.10.1 dev eth0 metric 1
> and this is ip route sh table hdsl:
> default via 1.1.1.1 dev eth0 metric 1
> 
> main table doesn't have any default route.
> 
> Locally generated packet with destination port 80
> are going through the adsl table but the packet
> source ip is 1.1.1.254. Why source ip packet is
> 1.1.1.254? Should't it be 10.10.10.6?

The mark value can't be used for source address selection
because at the time source address selection is performed
there is no packet yet and thus no mark value.