personal-firewall and an addon-script.

Hello, who can help me? I have Suse7.1 as NAT-Router and PacketFilter. Its running a PersonalFirewall but after the starting the personal-firewall I modified the system with "ipchains-restore < /etc/ipchains-rules to update the rules, I want to use. That's working fine, but when my dynamic-IP-Provider have canceled the Connection (after 24 hours) , I must always restart my script. What can I do after an IP-Change on PPP to do that automatic? Can I put the script in the IP-Up-Script? Sorry, my english isn't very good ;) Bye, Jost Schöler