mountd

SYNOPSIS
       /usr/sbin/rpc.mountd [options]

DESCRIPTION
       The  rpc.mountd program implements the NFS mount protocol. When receiv-
       ing 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  dae-
       mon.

       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.

       -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) envi-
              ronment. 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  argu-
              ments.  The first will be mount or unmount depending on the rea-
              son 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 sub-
              stantial 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 cryp-
              tographic  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.

       You have to use the daemon name mountd for the daemon name (even if the
       binary has a different name).

       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)