ip port-map command associates TCP or User Datagram Protocol (UDP) port numbers with applications or services, establishing a table of default port mapping information at the firewall. This information is used to support network environments that run services using ports that are different from the registered or well-known ports associated with a service or application.
When you issue the no form of the command, include all the parameters needed to remove the entry matching that specific set of parameters. For example, if you issued no ip port-map appl-name, then all entries for that application are removed.
The port mapping information in the PAM table is of one of three types:
?System-defined
?User-defined?Host-specific
System-Defined Port Mapping
Initially, PAM creates a set of system-defined entries in the mapping table using well-known or registered port mapping information set up during the system start-up. The Cisco IOS Firewall Context-Based Access Control (CBAC) feature requires the system-defined port mapping information to function properly.
You can delete or modify system-defined port mapping information. Use the no form of the command for deletion and the regular form of the command to remap information to another application. You can also add new port numbers to system-defined applications. However, for some system-defined applications like HTTP and Simple Mail Transfer Protocol (SMTP), in which the firewall inspects deeper into packets, their protocol (UDP or TCP) cannot be changed from that defined in the system.
