Tutorials Point

  Unix for Beginners
  Unix Shell Programming
  Advanced Unix
  Unix Useful References
  Unix Useful Resources
  Selected Reading

Copyright © 2014 by tutorialspoint

  Home     References     Discussion Forums     About TP  

portmap - Unix, Linux Command

previous next AddThis Social Bookmark Button



portmap - DARPA port to RPC program number mapper


portmap [-d] [-l] [-v]


Portmap is a server that converts RPC program numbers into DARPA protocol port numbers. It must be running in order to make RPC calls.

When an RPC server is started, it will tell portmap what port number it is listening to, and what RPC program numbers it is prepared to serve. When a client wishes to make an RPC call to a given program number, it will first contact portmap on the server machine to determine the port number where RPC packets should be sent.

Portmap must be started before any RPC servers are invoked.

Normally portmap forks and dissociates itself from the terminal like any other daemon. Portmap then logs errors using syslog(3).

Option available:

-d (debug) prevents portmap from running as a daemon, and causes errors and debugging information to be printed to the standard error output.
-l (localhost only) causes portmap to only bind to the loopback interface (i.e. INADDR_LOOPBACK).
-v (verbose) run portmap in verbose mode.

This portmap version is protected by the tcp_wrapper library. You have to give the clients access to portmap if they should be allowed to use it. To allow connects from clients of the .bar.com domain you could use the following line in /etc/hosts.allow:

portmap: .bar.com

You have to use the daemon name portmap for the daemon name (even if the binary has a different name). For the client names you can use the keyword ALL, IP addresses, hostnames or domain names.

For further information please have a look at the tcpd((8)), hosts_allow((5)) and hosts_access((5)) manual pages.


rpcinfo((8)), pmap_set((8)), pmap_dump((8)), xinetd((8)) tcpd((8)) hosts_access((5)) hosts_options((5))


If portmap crashes, all rpc servers must be restarted.


The portmap command appeared in BSD BSD 4.3.

previous next Printer Friendly