Many policy statements refer to how users access specific applications that are running within the network. Therefore, a policy agent must be able to determine the set of applications that are active at a server and determine the network header mappings that would be associated with those applications. Specifically, the policy management tool must be aware of the port numbers and protocol (TCP/UDP) that an application would be using.
For the purpose of identifying applications, they can be classified into two categories:
Applications in which at least one communicating party uses a fixed port. Most applications fall into this category. Typically, the server program listens on a well-known port number, and the client side ...