RE: UDP stream load balancing across multiple uplinks

["Barry A Rich" <barich@trisectrix.com>]

> -----Original Message-----
> From: netfilter-owner@vger.kernel.org
[mailto:netfilter-owner@vger.kernel.org]
> On Behalf Of Grant Taylor
> Sent: Friday, July 25, 2008 11:10 AM
> 
> Given that the source IP of your packets can change mid stream, you
> could use the "nth" match extension.  Using "nth" you would match
> packets to decide how to mark them and then use the mark to determine
> what routing table to use which would ultimately decide which outbound
> path to use.

The nth match looks promising. Given that I want to avoid connection
tracking, I tried the following commands:

iptables -t raw -A PREROUTING -i eth0 -p udp --sport $SPORT -m statistic
--mode nth --every 3 --packet 0 -j SNAT --to-source $UPLINK1IP
iptables -t raw -A PREROUTING -i eth0 -p udp --sport $SPORT -m statistic
--mode nth --every 3 --packet 1 -j SNAT --to-source $UPLINK2IP
iptables -t raw -A PREROUTING -i eth0 -p udp --sport $SPORT -m statistic
--mode nth --every 3 --packet 2 -j SNAT --to-source $UPLINK3IP

Each of these produce the following error:

	iptables: Invalid argument

Any suggestions on what is wrong? Is this the correct way to bypass
connection tracking?

Thanks.