rpc.mountd(8)						      System Manager's Manual						     rpc.mountd(8)

NAME

       rpc.mountd - NFS mount daemon

SYNOPSIS

       /usr/sbin/rpc.mountd [options]

DESCRIPTION

       The  rpc.mountd program implements the NFS mount protocol. When receiving a MOUNT request from an NFS client, it checks the request against
       the list of currently exported file systems. If the client is permitted to mount the file system, rpc.mountd  obtains  a  file  handle  for
       requested directory and returns it to the client.

   Exporting NFS File Systems
       Making file systems available to NFS clients is called exporting.

       Usually,  a file system and the hosts it should be made available to are listed in the /etc/exports file, and invoking exportfs -a whenever
       the system is booted. The exportfs(8) command makes export information available to both the kernel NFS server module  and  the	rpc.mountd
       daemon.

       Alternatively, you can export individual directories temporarily using exportfs's host:/directory syntax.

   The rmtab File
       For  every  mount  request  received from an NFS client, rpc.mountd adds an entry to the /var/lib/nfs/rmtab file. When receiving an unmount
       request, that entry is removed.

       However, this file is mostly ornamental. One, the client can continue to use the file handle even after calling rpc.mountd 's UMOUNT proce-
       dure. And two, if a client reboots without notifying rpc.mountd , a stale entry will remain in rmtab.

OPTIONS

       -d kind	or  --debug kind
	      Turn on debugging. Valid kinds are: all, auth, call, general and parse.

       -F  or  --foreground
	      Run in foreground (do not daemonize)

       -f  or  --exports-file
	      This  option  specifies  the exports file, listing the clients that this server is prepared to serve and parameters to apply to each
	      such mount (see exports(5)).  By default, export information is read from /etc/exports.

       -h  or  --help
	      Display usage message.

       -o num  or  --descriptors num
	      Set the limit of the number of open file descriptors to num. The default is to leave the limit unchanged.

       -N  or  --no-nfs-version
	      This option can be used to request that rpc.mountd do not offer certain versions of NFS. The current version of rpc.mountd can  sup-
	      port both NFS version 2 and the newer version 3. If the NFS kernel module was compiled without support for NFSv3, rpc.mountd must be
	      invoked with the option --no-nfs-version 3 .

       -n  or  --no-tcp
	      Don't advertise TCP for mount.

       -P     Ignored (compatibility with unfsd??).

       -p  or  --port num
	      Force rpc.mountd to bind to the specified port num, instead of using the random port number assigned by the portmapper.

       -H  or  --ha-callout prog
	      Specify a high availability callout program, which will receive callouts for all client mount  and  unmount  requests.  This  allows
	      rpc.mountd  to be used in a High Availability NFS (HA-NFS) environment. This callout is not needed (and should not be used) with 2.6
	      and later kernels (instead, mount the nfsd filesystem on /proc/fs/nfsd ).  The program will be called with 4 arguments.	The  first
	      will  be	mount or unmount depending on the reason for the callout.  The second will be the name of the client performing the mount.
	      The third will be the path that the client is mounting.  The last is the number of concurrent mounts that we believe the client  has
	      of that path.

       -s, --state-directory-path directory
	      specify a directory in which to place statd state information.  If this option is not specified the default of /var/lib/nfs is used.

       -r, --reverse-lookup
	      mountd tracks IP addresses in the rmtab, and when a DUMP request is made (by someone running showmount -a, for instance), it returns
	      IP addresses instead of hostnames by default. This option causes mountd to do a reverse lookup on each IP address  and  return  that
	      hostname instead. Enabling this can have a substantial negative effect on performance in some situations.

       -t N or --num-threads=N
	      This option specifies the number of worker threads that rpc.mountd spawns.  The default is 1 thread, which is probably enough.  More
	      threads are usually only needed for NFS servers which need to handle mount storms of hundreds of NFS mounts in  a  few  seconds,	or
	      when your DNS server is slow or unreliable.

       -V  or  --nfs-version
	      This option can be used to request that rpc.mountd offer certain versions of NFS. The current version of rpc.mountd can support both
	      NFS version 2 and the newer version 3.

       -v  or  --version
	      Print the version of rpc.mountd and exit.

       -g  or  --manage-gids
	      Accept requests from the kernel to map user id numbers into  lists of group id numbers for use in access control.   An  NFS  request
	      will normally (except when using Kerberos or other cryptographic authentication) contains a user-id and a list of group-ids.  Due to
	      a limitation in the NFS protocol, at most 16 groups ids can be listed.  If you use the -g flag, then the list of group ids  received
	      from  the  client will be replaced by a list of group ids determined by an appropriate lookup on the server. Note that the 'primary'
	      group id is not affected so a newgroup command on the client will still be effective.  This function requires a  Linux  Kernel  with
	      version at least 2.6.21.

TCP_WRAPPERS SUPPORT
       This  rpc.mountd  version  is  protected  by  the  tcp_wrapper library. You have to give the clients access to rpc.mountd 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:

       mountd: .bar.com

       You have to use the daemon name mountd for the daemon name (even if the binary has a different  name).	Note:  hostnames  used	in  either
       access file will be ignored when they can not be resolved into IP addresses.

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

SEE ALSO

       rpc.nfsd(8), exportfs(8), exports(5), rpc.rquotad(8).

FILES

       /etc/exports, /var/lib/nfs/xtab.

AUTHOR

       Olaf Kirch, H. J. Lu, G. Allan Morris III, and a host of others.

								    31 Aug 2004 						     rpc.mountd(8)