Re: Using MARK and TOS to route traffic through different interfaces to the same destination

[Pascal Hambourg <pascal.mail@plouf.fr.eu.org>]

Hello,

Thomas Jacob a écrit :
> On Thu, 2008-12-11 at 13:18 +0100, Javier Gálvez Guerrero wrote:
>>
>> I need to route packets through different interfaces (let them be ath0
>> and eth0) depending on the application source port, so I thought using
>> TOS or MARK targets of iptables would be helpful.
>>
>> Anyway, as I try configure it to mark the traffic and updating the
>> routing tables through many different ways, I can't get it working so
>> the packets are always sent through the "default" interface in the
>> main routing table.
>>
>> For example, if I use MARK I configure it this way:
>>
>> sudo iptables -A OUTPUT -t mangle -p tcp --dport 60301 -j MARK --set-mark 1
>> sudo iptables -A OUTPUT -t mangle -p tcp --dport 60302 -j MARK --set-mark 2

These rules match the destination port. Replace --dport with --sport to 
match the source port.

> AFAIK, locally generated packets are routed before they are sent to
> netfilter, so setting fwmarks there to influence routing is pointless.

A rerouting happens after the OUTPUT chains in order to take into 
account destination NAT and marks.