Can't get iptables redirect to work

[ilyail3]

Hi

I have a short snippet

CHAIN_NAME="RED$dest"

sudo iptables -t nat -L $CHAIN_NAME &> /dev/null

if [[ $? != 0 ]];
then
	echo "create $CHAIN_NAME"
	iptables -t nat -N $CHAIN_NAME
	iptables -t nat -A PREROUTING -p tcp --dport $dest -j $CHAIN_NAME
fi


iptables -t nat -F $CHAIN_NAME
iptables -t nat -A $CHAIN_NAME -p tcp -j REDIRECT --dport $dest --to-port $source

Which should allow multiple instances of a service to run at the same time, redirecting to the newest on and gracefully shutting down the old one without causeing downtime. Well, at least that's the theory.

In practice, I couldn't get it to work on my development environment , ubutntu 11.10 64bit desktop.

I tried using

sudo sysctl -w net.ipv4.ip_forward=1

, Masquerading, allowing forward(which is allowed anyway). And still couldn't get it to work.

I used similar script on server and it worked like a charm, why is Desktop different?

[ilyail3]

Found something running

sudo iptables -t nat -v -x -n -L
Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
    pkts      bytes target     prot opt in     out     source               destination         
       0        0 LOG        all  --  *      *       0.0.0.0/0            0.0.0.0/0           LOG flags 0 level 4 

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
    pkts      bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 222 packets, 14344 bytes)
    pkts      bytes target     prot opt in     out     source               destination         

Chain POSTROUTING (policy ACCEPT 222 packets, 14344 bytes)
    pkts      bytes target     prot opt in     out     source               destination

why I don't have and prerouting packets, is there something I forgot to enable?