Stateless NAT

[Matin Tamizi <mtamizi@gmail.com>]

I'm trying to setup stateless NAT on a testbed I'm using for
university research on DDoS.  We are developing a stateless DDoS
prevention tool, but to test the software I need to use stateless NAT
to force traffic from outside through one computer, the router, and to
the victim.

I tried the NETMAP target module, but the router is still filtering my
out of state packets from the attack.  The following show the rules in
my nat table:

root # iptables -t nat -L
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
NETMAP     all  --  anywhere             <victim's ip address> 192.168.13.2/32

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination
SNAT       all  --  192.168.13.2         anywhere           
to:<victim's ip address>

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

I appreciate any suggestions on how I could correct my setup so I can
use stateless.