Why does a NFS or NIS service block the port of another service?

Solution Verified - Updated -


  • CUPS fails to start. It cannot bind to port 631. netstat -tulpen | grep :631 shows an NFS or NIS service is bound to this port.
  • Why would portmap give out as a random port a well-known port 995 (POP3 SSL) to rpc.statd?
  • Why can't portmap assign a random port from unprivileged (> 1024) ports only?


  • Red Hat Enterprise Linux
  • NFS and/or NIS services configured

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