Port assignments

Port numbers are used on various socket calls. They are also included in both the header of a TCP segment and a UDP datagram. You can assign port numbers to your own server applications by adding entries to the z/OS® UNIX file or to the data set.

Guidelines:

Assign ports is by assigning a standard port number and use the Server Bind Control function of the PROFILE.TCPIP PORT statement to assign each server to a separate IP address.
Use the IP address on the PORT BIND be a VIPA address known to the domain name server (DNS) as a host name that users understand. For example, the RXSERVE procedure is assigned to ports 512 and 514, the orexecd and orshd daemons are assigned to ports 512 and 514, and two IP addresses (host names MVS97 and MVS97USS) 9.67.113.1 and 9.67.113.2 are available.

The following example reflects a situation where more than one application needs to listen on the same port, and the application or applications bind to INADDR_ANY.

In this example, the PORT statement would be as follows:

PORT
512 TCP RXSERVE ; Remote Execution Server (default)
512 TCP OMVS BIND 9.67.113.2 ; orexecd Remote Execution Server (MVS97USS)
514 TCP RXSERVE ; Remote Shell Server (default)
514 TCP OMVS BIND 9.67.113.2 ; orshd Remote Shell Server (MVS97USS)

Result: Clients who use MVS97 for remote execution get RXSERVE, and clients who use MVS97USS get OMVS orshd.