xref: /freebsd/usr.sbin/mountd/mountd.8 (revision cce11997a052549933ca1c4d7412bf51137e4d0b)

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.Dd April 8, 2024
.Dt MOUNTD 8
.Os
.Sh NAME
.Nm mountd
.Nd service remote
.Tn NFS
mount requests
.Sh SYNOPSIS
.Nm
.Op Fl 2AdelnRrS
.Op Fl h Ar bindip
.Op Fl p Ar port
.Op Ar exportsfile ...
.Sh DESCRIPTION
The
.Nm
utility is the server for
.Tn NFS
mount requests from other client machines.
It listens for service requests at the port indicated in the
.Tn NFS
server specification; see
.%T "Network File System Protocol Specification" ,
RFC1094, Appendix A and
.%T "NFS: Network File System Version 3 Protocol Specification" ,
RFC1813, Appendix I.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl 2
Allow the administrator to force clients to use only the
version 2
.Tn NFS
protocol to mount file systems from this server.
.It Fl A
Silence the warnings related to
.Dq administrative controls .
These warnings remind users that an exported
.Dq administrative control
directory that is not a local server file system mount point
actually exports the entire local file system and not just
the subtree below the directory exported.
(See
.Xr exports 5 )
.It Fl d
Output debugging information.
.Nm
will not detach from the controlling terminal and will print
debugging messages to stderr.
.It Fl e
Ignored; included for backward compatibility.
.It Fl h Ar bindip
Specify specific IP addresses to bind to for TCP and UDP requests.
This option may be specified multiple times.
If no
.Fl h
option is specified,
.Nm
will bind to
.Dv INADDR_ANY .
Note that when specifying IP addresses with
.Fl h ,
.Nm
will automatically add
.Li 127.0.0.1
and if IPv6 is enabled,
.Li ::1
to the list.
.It Fl l
Cause all succeeded
.Nm
requests to be logged.
.It Fl n
Allow non-root mount requests to be served.
This should only be specified if there are clients such as PC's,
that require it.
It will automatically clear the vfs.nfsd.nfs_privport sysctl flag, which
controls if the kernel will accept NFS requests from reserved ports only.
.It Fl p Ar port
Force
.Nm
to bind to the specified port, for both
.Dv AF_INET
and
.Dv AF_INET6
address families.
This is typically done to ensure that the port which
.Nm
binds to is a known quantity which can be used in firewall rulesets.
If
.Nm
cannot bind to this port, an appropriate error will be recorded in
the system log, and the daemon will then exit.
.It Fl R
Do not support the Mount protocol and do not register with
.Xr rpcbind 8 .
This can be done for NFSv4 only servers, since the Mount protocol is not
used by NFSv4.
Useful for NFSv4 only servers that do not wish to run
.Xr rpcbind 8 .
.Xr showmount 8
will not work, however since NFSv4 mounts are not shown by
.Xr showmount 8 ,
this should not be an issue for an NFSv4 only server.
.It Fl r
Allow mount RPCs requests for regular files to be served.
Although this seems to violate the mount protocol specification,
some diskless workstations do mount requests for
their swapfiles and expect them to be regular files.
Since a regular file cannot be specified in
.Pa /etc/exports ,
the entire file system in which the swapfiles resides
will have to be exported with the
.Fl alldirs
flag.
.It Ar exportsfile
Specify an alternate location
for the exports file.
More than one exports file can be specified.
.It Fl S
Tell mountd to suspend/resume execution of the nfsd threads whenever
the exports list is being reloaded.
This avoids intermittent access
errors for clients that do NFS RPCs while the exports are being
reloaded, but introduces a delay in RPC response while the reload
is in progress.
If
.Nm
crashes while an exports load is in progress,
.Nm
must be restarted to get the nfsd threads running again, if this
option is used.
.El
.Pp
When
.Nm
is started,
it loads the export host addresses and options into the kernel
using the
.Xr nmount 2
system call.
After changing the exports file,
a hangup signal should be sent to the
.Nm
daemon
to get it to reload the export information.
After sending the SIGHUP
(kill \-s HUP `cat /var/run/mountd.pid`),
check the syslog output to see if
.Nm
logged any parsing
errors in the exports file.
.Pp
If multiple instances of
.Nm
are being run, either in multiple jails or both within
and outside of a jail, care must be taken to export
any given file system in only one of the instances.
Note that the
.Va allow.nfsd
jail parameter is required to allow
.Nm
to run in a jail.
See
.Xr jail 8
for more information.
.Pp
If
.Nm
detects that the running kernel does not include
.Tn NFS
support, it will attempt to load a loadable kernel module containing
.Tn NFS
code, using
.Xr kldload 2 .
If this fails, or no
.Tn NFS
KLD was available,
.Nm
exits with an error.
When run in a jail, the
.Xr kldload 2
must be done outside the jail, typically by adding
.Dq nfsd
to
.Va kld_list
in the
.Xr rc.conf 5
file on the jail host.
.Sh FILES
.Bl -tag -width /var/run/mountd.pid -compact
.It Pa /etc/exports
the list of exported file systems
.It Pa /var/run/mountd.pid
the pid of the currently running mountd
.It Pa /var/db/mountdtab
the current list of remote mounted file systems
.El
.Sh SEE ALSO
.Xr nfsstat 1 ,
.Xr kldload 2 ,
.Xr nfsv4 4 ,
.Xr exports 5 ,
.Xr rc.conf 5 ,
.Xr jail 8 ,
.Xr nfsd 8 ,
.Xr rpcbind 8 ,
.Xr showmount 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Bx 4.4 .