What wrong with my ipchains script?
1. It's in the wrong place: initialisation usially is done with /etc/rc.* scripts.
2. It's not a "proper" firewall script: it doesn't cover the "basics".
3. If you have problems doing basic troubleshooting, try add logging.
Check out the
LQ FAQ: Security references, post #2, "Netfilter, firewall, Iptables, Ipchains, DoS, DDoS" for some HOWTO's.