Port Mapper

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What Does Port Mapper Mean?

A port mapper is the protocol that maps the number or version of an Open Network Computing Remote Procedure Call (ONC RPC) program to a port used for networking by that version of the program. Upon initiation, the ONC RPC server requests the port mapper to assign a port number for each program using the transport protocol for file transfer or communication purposes. Therefore programs use a port mapper to determine which port is assigned to them before using it.

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Techopedia Explains Port Mapper

The port mapper assigns a unique TCP/UDP protocol port number to an RPC program. Upon starting, the Network File System uses a port map to listen to and send data to specific ports. Applications or processes that use the TCP/UDP protocol also use a port mapper, which assigns them a unique port number that they can use to make a connection. This is especially useful in ONC RPC servers where the port mapper determines the ports to be used upon initiation. The port mapper must always start before any other RPC server is started. Several developers have developed port mappers that perform port assignment for programs requiring it. Since a port mapper works on ports, its main work is in the transport layer.

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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.