exportd(8) — Linux manual page


nfsv4.exportd(8)         System Manager's Manual        nfsv4.exportd(8)

NAME         top

       nfsv4.exportd - NFSv4 Server Mount Daemon

SYNOPSIS         top

       /usr/sbin/nfsv4.exportd [options]

DESCRIPTION         top

       The nfsv4.exportd is used to manage NFSv4 exports.  The NFS
       server (nfsd) maintains a cache of authentication and
       authorization information which is used to identify the source of
       each request, and then what access permissions that source has to
       any local filesystem.  When required information is not found in
       the cache, the server sends a request to nfsv4.exportd to fill in
       the missing information.  nfsv4.exportd uses a table of
       information stored in /var/lib/nfs/etab and maintained by
       exportfs(8), possibly based on the contents of exports(5), to
       respond to each request.

OPTIONS         top

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

       -l or --log-auth
              Enable logging of responses to authentication and access
              requests from nfsd.  Each response is then cached by the
              kernel for 30 minutes (or as set by --ttl below), and will
              be refreshed after 15 minutes (half the ttl time) if the
              relevant client remains active.  Note that -l is
              equivalent to -d auth and so can be enabled in
              /etc/nfs.conf with "debug = auth" in the [exportd]

       -i or --cache-use-ipaddr
              Normally each client IP address is matched against each
              host identifier (name, wildcard, netgroup etc) found in
              /etc/exports and a combined identity is formed from all
              matching identifiers.  Often many clients will map to the
              same combined identity so performing this mapping reduces
              the number of distinct access details that the kernel
              needs to store.  Specifying the -i option suppresses this
              mapping so that access to each filesystem is requested and
              cached separately for each client IP address.  Doing this
              can increase the burden of updating the cache slightly,
              but can make the log messages produced by the -l option
              easier to read.

       -T  or  --ttl
              Provide a time-to-live (TTL) for cached information given
              to the kernel.  The kernel will normally request an update
              if the information is needed after half of this time has
              expired.  Increasing the provided number, which is in
              seconds, reduces the rate of cache update requests, and
              this is particularly noticeable when these requests are
              logged with -l.  However increasing also means that
              changes to hostname to address mappings can take longer to
              be noticed.  The default TTL is 1800 (30 minutes).

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

       -h  or  --help
              Display usage message.

       -t N or --num-threads=N or --num-threads N
              This option specifies the number of worker threads that
              nfsv4.exports 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.

       -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) contain 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.


       Many of the options that can be set on the command line can also
       be controlled through values set in the [exportd] or, in some
       cases, the [nfsd] sections of the /etc/nfs.conf configuration
       file.  Values recognized in the [exportd] section include
       cache-use-ipaddr , ttl, manage-gids, and debug which each have
       the same effect as the option with the same name.

FILES         top

              input file for exportfs, listing exports, export options,
              and access control lists

SEE ALSO         top

       exportfs(8), exports(5), showmount(8), nfs.conf(5),

       RFC 7530 - "Network File System (NFS) Version 4 Protocol"
       RFC 8881 - "Network File System (NFS) Version 4 Minor Version 1

COLOPHON         top

       This page is part of the nfs-utils (NFS utilities) project.
       Information about the project can be found at 
       ⟨http://linux-nfs.org/wiki/index.php/Main_Page⟩.  If you have a
       bug report for this manual page, see
       ⟨http://linux-nfs.org/wiki/index.php/Main_Page⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨git://git.linux-nfs.org/projects/steved/nfs-utils.git⟩ on
       2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-05-10.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

                               02 Feb 2021              nfsv4.exportd(8)

Pages that refer to this page: nfs.conf(5)exportfs(8)