21.9. NFS and portmap
portmapservice for backward compatibility.
portmappermaps RPC services to the ports they are listening on. RPC processes notify
portmapwhen they start, registering the ports they are listening on and the RPC program numbers they expect to serve. The client system then contacts
portmapon the server with a particular RPC program number. The
portmapservice redirects the client to the proper port number so it can communicate with the requested service.
portmapto make all connections with incoming client requests,
portmapmust be available before any of these services start.
portmapservice uses TCP wrappers for access control, and access control rules for
portmapaffect all RPC-based services. Alternatively, it is possible to specify access control rules for each of the NFS RPC daemons. The man pages for
rpc.statdcontain information regarding the precise syntax for these rules.
21.9.1. Troubleshooting NFS and
portmapprovides coordination between RPC services and the port numbers used to communicate with them, it is useful to view the status of current RPC services using
portmapwhen troubleshooting. The
rpcinfocommand shows each RPC-based service with port numbers, an RPC program number, a version number, and an IP protocol type (TCP or UDP).
portmap, issue the following command as root:
program vers proto port 100000 2 tcp 111 portmapper 100000 2 udp 111 portmapper 100021 1 udp 32774 nlockmgr 100021 3 udp 32774 nlockmgr 100021 4 udp 32774 nlockmgr 100021 1 tcp 34437 nlockmgr 100021 3 tcp 34437 nlockmgr 100021 4 tcp 34437 nlockmgr 100011 1 udp 819 rquotad 100011 2 udp 819 rquotad 100011 1 tcp 822 rquotad 100011 2 tcp 822 rquotad 100003 2 udp 2049 nfs 100003 3 udp 2049 nfs 100003 2 tcp 2049 nfs 100003 3 tcp 2049 nfs 100005 1 udp 836 mountd 100005 1 tcp 839 mountd 100005 2 udp 836 mountd 100005 2 tcp 839 mountd 100005 3 udp 836 mountd 100005 3 tcp 839 mountd
portmapis unable to map RPC requests from clients for that service to the correct port. In many cases, if NFS is not present in
rpcinfooutput, restarting NFS causes the service to correctly register with
portmapand begin working. For instructions on starting NFS, refer to Section 21.5, “Starting and Stopping NFS”.
rpcinfocommand. Refer to the
rpcinfoman page for more information.