nfsd
NFSD(8) System Manager's Manual NFSD(8)
NAME
nfsd – NFS server daemon
SYNOPSIS
nfsd [command]
nfsd [-F exports_file] checkexports
nfsd [-NRrtuv] [-F exports_file] [-n num_servers] [-p nfsport]
[-P mountport] [command]
DESCRIPTION
nfsd runs on an NFS server machine to service NFS and MOUNT protocol
requests from NFS client machines. In order for a machine to act as an NFS
server an NFS exports file, /etc/exports, must exist and the nfsd service
must be enabled.
nfsd listens for NFS service requests at the port indicated in the NFS
server specification (2049) and the mountd thread listens for MOUNT service
requests at an available port registered with portmap(8).
For more information on the NFS and MOUNT protocols see Network File System
Protocol Specification, RFC1094 and NFS: Network File System Version 3
Protocol Specification.
The nfsd daemon is a multi-threaded process that includes a number of
threads processing NFS requests, a thread to accept new socket connections
and a thread that processes NFS MOUNT protocol requests.
When nfsd is started, it loads the export host addresses and options into
the kernel using the nfssvc(2) system call. After changing the list of
exports (either directly or indirectly via a change in netgroup
membership), a hangup signal should be sent to the daemon to get it to
reload the export information. This can be accomplished with the update
command described below.
Any errors encountered while processing the export entries will be logged
via syslog(3).
nfsd is normally launched by launchd(8); however, the nfsd command may also
be used to manipulate the service using the following commands:
enable Enables the nfsd service.
disable Disables the nfsd service.
start Starts the nfsd service. Note: if the service is disabled it will
not be restarted on reboot. Use the enable command to make the
change permanent.
stop Stops the nfsd service. Note: if the service is enabled it will
be restarted on reboot. Use the disable command to make the
change permanent.
restart Restarts the nfsd service (by stopping the service - it will
restart automatically if the /etc/exports file exists).
update Sends a SIGHUP to the running nfsd daemon to cause it to update
its configuration.
status Displays whether the nfsd service is enabled and whether the nfsd
daemon is currently running.
checkexports
Checks the exports file and reports any errors (to stderr). Note
that this can be useful to verify the validity of an alternate
exports file (using the -F option below) prior to putting the
changes in place and updating nfsd.
verbose [up|down]+
Sends USR1 and/or USR2 signal(s) to the running nfsd daemon to
cause it to increase and/or decrease its logging level. (See
below for details about nfsd's logging).
Logging is performed via syslog(3) using the LOG_DAEMON facility. By
default, only messages up to priority LOG_WARNING are logged. Setting the
verbose level to one will add LOG_NOTICE messages which includes logging
failed mount attempts. A verbose level of two will increase the log level
to LOG_INFO which includes logging successful mount attempts. A log level
of three or more will add LOG_DEBUG messages and cause increasing amounts
of debug information to be logged. The debug information exposes lots of
information about nfsd's inner workings which is typically only useful to
developers. Note: the syslog(8) configuration may need to be adjusted in
order to see the increased verbosity.
The nfsd utility exits 0 on success, and >0 if an error occurs. When given
the status command, it exits 0 if the service is enabled, and 1 if the
service is disabled.
The following is a list of command line options that are available.
However, since nfsd is normally started by launchd(8), configuration of
these options should be controlled using the equivalent settings in the NFS
configuration file (see nfs.conf(5)).
-F exports_file
The exports_file argument specifies an alternate location for the
exports file (useful with the checkexports command).
-N Allow non-root mount requests to be served. This should only be
specified if there are clients that require it.
-P # Specifies which port to use for the MOUNT service.
-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 /etc/exports, the -alldirs option will need to be used
on the export in which the swap files reside.
-n # Specifies how many NFS server threads to create.
-p # Specifies which port to use for the NFS service (instead of the
default of 2049).
-r Register the NFS service with portmap(8). This option can be used
to re-register the NFS services if the portmap server is restarted.
This option is equivalent to the update command.
-t Serve TCP NFS clients. Note: only TCP will be used if no other
options are specified.
-u Serve UDP NFS clients. Note: only UDP will be used if no other
options are specified.
-v Increase nfsd's logging level by one (may be used multiple times).
CONFIGURATION
Unless otherwise specified, eight NFS server threads are started and both
UDP and TCP transports are supported.
A server should run enough threads to handle the maximum level of
concurrency from its clients.
See nfs.conf(5) for a list of tunable parameters.
NOTES
The exports list displayed via showmount(8) may contain additional
information about the status of each export. This information is reported
as entries in the export's group list.
If an export is currently unavailable, the group list will begin with the
entry "<offline>" (or "<offline*>" if it is unavailable to some but not all
clients exported to).
If an export allows non-default security mechanisms, the group list will
contain an entry indicating what security mechanisms are allowed. For
example: "<krb5:sys>". The mechanisms are listed in no particular order
and may not be available to all clients.
If an export is available to all clients, the group list is usually empty.
But if additional status information is returned in the group list, then
the list will also contain an explicit "(Everyone)" entry to indicate that
the export is available to all clients.
If nfsd does not have read access to an export, mount would fail with
"Permission denied" and checkexports command would report the following
error:
sandbox_check failed. nfsd has no read access to <path>
This could be resolved by granting nfsd "Full Disk Access" under "Privacy"
tab of the "Security & Privacy" preference in the "System Preferences"
followed by restart of nfsd service.
FILES
/etc/exports The list of exported filesystems.
/var/run/nfsd.pid The pid of the currently running nfsd.
/var/run/mountd.pid The pid of the currently running mountd (provided
for backwards compatibility with scripts that may
HUP mountd to update exports).
/var/run/mountdtab The current list of outstanding mounts served.
/var/run/mountdexptab Information about exported file systems and
directories (UUIDs, handles, ...).
/System/Library/LaunchDaemons/com.apple.nfsd.plist
The nfsd service's property list file for
launchd(8).
SEE ALSO
exports(5), nfs.conf(5), showmount(8), nfsstat(1), nfssvc(2), portmap(8),
rpc.rquotad(8), launchd(8)
HISTORY
The nfsd and mountd utilities first appeared in 4.4BSD. mountd
functionality was merged into nfsd in Darwin 9.
macOS 12.1 November 10, 2008 macOS 12.1