Allow me rewrite and clarify my question, I was not clear: I need to setup iptables on system A to drop packets from all IPs except packets coming from system B. System B has dynamic IP (dynip.sh). B's DNS name is known but B's IP is not fixed. What are my options to setup iptables on A ? Y.L. -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html