What does destination port number ZZZZ mean?
All the traffic going through the firewall is part of a connection. A connection consists of the pair of IP addresses that are talking to each other, as well a pair of port numbers. The destination port number often indicates the type of service being connected to. When a firewall blocks a connection, it will save the destination port number to its logfile. This section describes some of the meanings of these port numbers. Port numbers are divided into three ranges: • The Well Known Ports are those from 0 through 1023. These are tightly bound to services, and usually traffic on this port clearly indicates the protocol for that service. For example, port 80 virtually always indicates HTTP traffic. • The Registered Ports are those from 1024 through 49151. These are loosely bound to services, which means that while there are numerous services “bound” to these ports, these ports are likewise used for many other purposes. For example, most systems start handing out dynamic ports starting ar
