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Manual Pages  — MOUNTD


mountd – service remote NFS mount requests



mountd [-2delnRrS] [-h bindip] [-p port] [exportsfile ...]


The mountd utility is the server for NFS mount requests from other client machines. It listens for service requests at the port indicated in the NFS server specification; see Network File System Protocol Specification, RFC1094, Appendix A and NFS: Network File System Version 3 Protocol Specification, RFC1813, Appendix I.

The following options are available:
  Allow the administrator to force clients to use only the version 2 NFS protocol to mount file systems from this server.
  Output debugging information. mountd will not detach from the controlling terminal and will print debugging messages to stderr.
  Ignored; included for backward compatibility.
-h bindip
  Specify specific IP addresses to bind to for TCP and UDP requests. This option may be specified multiple times. If no -h option is specified, mountd will bind to INADDR_ANY. Note that when specifying IP addresses with -h, mountd will automatically add and if IPv6 is enabled, ::1 to the list.
  Cause all succeeded mountd requests to be logged.
  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.
-p port
  Force mountd to bind to the specified port, for both AF_INET and AF_INET6 address families. This is typically done to ensure that the port which mountd binds to is a known quantity which can be used in firewall rulesets. If mountd cannot bind to this port, an appropriate error will be recorded in the system log, and the daemon will then exit.
  Do not support the Mount protocol and do not register with 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 rpcbind(8). showmount(8) will not work, however since NFSv4 mounts are not shown by showmount(8), this should not be an issue for an NFSv4 only server.
  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 entire file system in which the swapfiles resides will have to be exported with the -alldirs flag.
  Specify an alternate location for the exports file. More than one exports file can be specified.
  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 mountd crashes while an exports load is in progress, mountd must be restarted to get the nfsd threads running again, if this option is used.

When mountd is started, it loads the export host addresses and options into the kernel using the mount(2) system call. After changing the exports file, a hangup signal should be sent to the mountd 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 mountd logged any parsing errors in the exports file.

If mountd detects that the running kernel does not include NFS support, it will attempt to load a loadable kernel module containing NFS code, using kldload(2). If this fails, or no NFS KLD was available, mountd exits with an error.


/etc/exports the list of exported file systems
  the pid of the currently running mountd
/var/db/mountdtab the current list of remote mounted file systems


nfsstat(1), kldload(2), nfsv4(4), exports(5), nfsd(8), rpcbind(8), showmount(8)


The mountd utility first appeared in BSD 4.4 .

MOUNTD (8) October 11, 2020

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