DoS Protection Profiles and Policy Rules work together to provide protection against flooding of many incoming SYN, UDP, ICMP, and ICMPv6 packets, and other types of IP packets. You determine what thresholds constitute flooding. In general, the DoS Protection profile sets the thresholds at which the firewall generates a DoS alarm, takes action such as Random Early Drop, and drops additional incoming connections. A DoS Protection policy rule configured to protect (rather than to allow or deny packets) determines the criteria for packets to match (such as source address) in order to be counted toward the thresholds. This flexibility allows you to block certain traffic, or allow certain traffic and treat other traffic as DoS traffic. When the incoming rate exceeds your maximum threshold, the firewall blocks incoming traffic from the source address.