From Linux Man Pages
rpc.mountd - NFS mount daemon
/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 procedure. 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 ver-
sion of rpc.mountd can support 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 depend-
ing 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.
-P, --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.
-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.
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).
For further information please have a look at the tcpd(8) and hosts_access(5) manual pages.
RELATED
rpc.nfsd(8), exportfs(8), exports(5), rpc.rquotad(8).
FILES
/etc/exports, /var/lib/nfs/xtab.
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