I have one problem but i think that it can be solved

I have in one pc box ( on slackware 9.0 ) two NIC's one connected to ADSL modem ( ADSl over pppoe ) the other to internal network.
On this box i also have freeswan (ipsec0) and i',m running iptables for firewall.
So here is what, vpn trafic must go to vpn tunnel, other trafic ( http, ftp ... ) must go to internet ( MASQ with iptables )
Now when i start ADSL and freeswan it all works ok but when i start iptables freeswan stops working. I have opened ports in my rc.firewall for fresswan but it won't work.
So if anyone has any idea about this pls let me know.
regards, pchammer