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EXPORTS(5)		  FreeBSD File Formats Manual		    EXPORTS(5)

NAME
     exports --	define remote mount points for NFS mount requests

SYNOPSIS
     exports

DESCRIPTION
     The exports file specifies	remote mount points for	the NFS	mount protocol
     per the NFS server	specification; see Network File	System Protocol
     Specification, RFC1094, Appendix A	and NFS: Network File System Version 3
     Specification, Appendix I.

     Each line in the file (other than comment lines that begin	with a #)
     specifies the mount point(s) and export flags within one local server
     file system or the	NFSv4 tree root	for one	or more	hosts.	A long line
     may be split over several lines by	ending all but the last	line with a
     backslash (`\').  A host may be specified only once for each local	file
     or	the NFSv4 tree root on the server and there may	be only	one default
     entry for each server file	system that applies to all other hosts.	 The
     latter exports the	file system to the ``world'' and should	be used	only
     when the file system contains public information.

     In	a mount	entry, the first field(s) specify the directory	path(s)	within
     a server file system that can be mounted on by the	corresponding
     client(s).	 There are three forms of this specification.  The first is to
     list all mount points as absolute directory paths separated by white-
     space.  This list of directory paths should be considered an
     ``administrative control'', since it is only enforced by the mountd(8)
     daemon and	not the	kernel.	 As such, it only applies to NFSv2 and NFSv3
     mounts and	only with respect to the client's use of the mount protocol.
     The second	is to specify the pathname of the root of the file system fol-
     lowed by the -alldirs flag; this form allows the host(s) to mount at any
     point within the file system, including regular files if the -r option is
     used on mountd(8).	 Because NFSv4 does not	use the	mount protocol,	the
     ``administrative controls'' are not applied.  Thus, all the above export
     line(s) should be considered to have the -alldirs flag, even if the line
     is	specified without it.  The third form has the string ``V4:'' followed
     by	a single absolute path name, to	specify	the NFSv4 tree root.  This
     line does not export any file system, but simply marks where the root of
     the server's directory tree is for	NFSv4 clients.	The exported file sys-
     tems for NFSv4 are	specified via the other	lines in the exports(5)	file
     in	the same way as	for NFSv2 and NFSv3.  The pathnames must not have any
     symbolic links in them and	should not have	any ``.'' or ``..'' compo-
     nents.  Mount points for a	file system may	appear on multiple lines each
     with different sets of hosts and export options.

     The second	component of a line specifies how the file system is to	be
     exported to the host set.	The option flags specify whether the file sys-
     tem is exported read-only or read-write and how the client	UID is mapped
     to	user credentials on the	server.	 For the NFSv4 tree root, the only
     option that can be	specified in this section is -sec.

     Export options are	specified as follows:

     -maproot=user The credential of the specified user	is used	for remote
     access by root.  The credential includes all the groups to	which the user
     is	a member on the	local machine (see id(1)).  The	user may be specified
     by	name or	number.

     -maproot=user:group1:group2:... The colon separated list is used to spec-
     ify the precise credential	to be used for remote access by	root.  The
     elements of the list may be either	names or numbers.  Note	that user:
     should be used to distinguish a credential	containing no groups from a
     complete credential for that user.

     -mapall=user or -mapall=user:group1:group2:... specifies a	mapping	for
     all client	UIDs (including	root) using the	same semantics as -maproot.

     The option	-r is a	synonym	for -maproot in	an effort to be	backward com-
     patible with older	export file formats.

     In	the absence of -maproot	and -mapall options, remote accesses by	root
     will result in using a credential of -2:-2.  All other users will be
     mapped to their remote credential.	 If a -maproot option is given,	remote
     access by root will be mapped to that credential instead of -2:-2.	 If a
     -mapall option is given, all users	(including root) will be mapped	to
     that credential in	place of their own.

     -sec=flavor1:flavor2... specifies a colon separated list of acceptable
     security flavors to be used for remote access.  Supported security	fla-
     vors are sys, krb5, krb5i and krb5p.  If multiple flavors are listed,
     they should be ordered with the most preferred flavor first.  If this
     option is not present, the	default	security flavor	list of	just sys is
     used.

     The -ro option specifies that the file system should be exported read-
     only (default read/write).	 The option -o is a synonym for	-ro in an
     effort to be backward compatible with older export	file formats.

     WebNFS exports strictly according to the spec (RFC	2054 and RFC 2055) can
     be	done with the -public flag.  However, this flag	in itself allows r/w
     access to all files in the	file system, not requiring reserved ports and
     not remapping UIDs.  It is	only provided to conform to the	spec, and
     should normally not be used.  For a WebNFS	export,	use the	-webnfs	flag,
     which implies -public, -mapall=nobody and -ro.  Note that only one	file
     system can	be WebNFS exported on a	server.

     A -index=file option can be used to specify a file	whose handle will be
     returned if a directory is	looked up using	the public filehandle
     (WebNFS).	This is	to mimic the behavior of URLs.	If no -index option is
     specified,	a directory filehandle will be returned	as usual.  The -index
     option only makes sense in	combination with the -public or	-webnfs	flags.

     Specifying	the -quiet option will inhibit some of the syslog diagnostics
     for bad lines in /etc/exports.  This can be useful	to avoid annoying
     error messages for	known possible problems	(see EXAMPLES below).

     The third component of a line specifies the host set to which the line
     applies.  The set may be specified	in three ways.	The first way is to
     list the host name(s) separated by	white space.  (Standard	Internet
     ``dot'' addresses may be used in place of names.)	The second way is to
     specify a ``netgroup'' as defined in the netgroup file (see netgroup(5)).
     The third way is to specify an Internet subnetwork	using a	network	and
     network mask that is defined as the set of	all hosts with addresses
     within the	subnetwork.  This latter approach requires less	overhead
     within the	kernel and is recommended for cases where the export line
     refers to a large number of clients within	an administrative subnet.

     The first two cases are specified by simply listing the name(s) separated
     by	whitespace.  All names are checked to see if they are ``netgroup''
     names first and are assumed to be hostnames otherwise.  Using the full
     domain specification for a	hostname can normally circumvent the problem
     of	a host that has	the same name as a netgroup.  The third	case is	speci-
     fied by the flag -network=netname[/prefixlength] and optionally
     -mask=netmask.  The netmask may be	specified either by attaching a
     prefixlength to the -network option, or by	using a	separate -mask option.
     If	the mask is not	specified, it will default to the mask for that	net-
     work class	(A, B or C; see	inet(4)).  See the EXAMPLES section below.

     Scoped IPv6 address must carry scope identifier as	documented in
     inet6(4).	For example, ``fe80::%re2/10'' is used to specify fe80::/10 on
     re2 interface.

     For the third form	which specifies	the NFSv4 tree root, the directory
     path specifies the	location within	the server's file system tree which is
     the root of the NFSv4 tree.  All entries of this form must	specify	the
     same directory path.  This	location can be	any directory and does not
     need to be	within an exported file	system.	If it is not in	an exported
     file system, a very limited set of	operations are permitted, so that an
     NFSv4 client can traverse the tree	to an exported file system.  Although
     parts of the NFSv4	tree can be non-exported, the entire NFSv4 tree	must
     consist of	local file systems capable of being exported via NFS.  NFSv4
     does not use the mount protocol and does permit clients to	cross server
     mount point boundaries, although not all clients are capable of crossing
     the mount points.

     The -sec option on	these line(s) specifies	what security flavors may be
     used for NFSv4 operations that do not use file handles. Since these oper-
     ations (SetClientID, SetClientIDConfirm, Renew, DelegPurge	and Release-
     LockOnwer)	allocate/modify	state in the server, it	is possible to
     restrict some clients to the use of the krb5[ip] security flavors,	via
     this option.  See the EXAMPLES section below.  This third form is mean-
     ingless for NFSv2 and NFSv3 and is	ignored	for them.

     The mountd(8) utility can be made to re-read the exports file by sending
     it	a hangup signal	as follows:

	   /etc/rc.d/mountd reload

     After sending the SIGHUP, check the syslogd(8) output to see whether
     mountd(8) logged any parsing errors in the	exports	file.

FILES
     /etc/exports  the default remote mount-point file

EXAMPLES
	   /usr	/usr/local -maproot=0:10 friends
	   /usr	-maproot=daemon	grumpy.cis.uoguelph.ca 131.104.48.16
	   /usr	-ro -mapall=nobody
	   /u -maproot=bin: -network 131.104.48	-mask 255.255.255.0
	   /a -network 192.168.0/24
	   /a -network 3ffe:1ce1:1:fe80::/64
	   /u2 -maproot=root friends
	   /u2 -alldirs	-network cis-net -mask cis-mask
	   /cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask	255.255.255.0
	   /private -sec=krb5i
	   /secret -sec=krb5p
	   V4: /   -sec=krb5:krb5i:krb5p -network 131.104.48 -mask 255.255.255.0
	   V4: /   -sec=sys:krb5:krb5i:krb5p grumpy.cis.uoguelph.ca

     Given that	/usr, /u, /a and /u2 are local file system mount points, the
     above example specifies the following:

     The file system rooted at /usr is exported	to hosts friends where friends
     is	specified in the netgroup file with users mapped to their remote cre-
     dentials and root mapped to UID 0 and group 10.  It is exported read-
     write and the hosts in ``friends''	can mount either /usr or /usr/local.
     It	is exported to 131.104.48.16 and grumpy.cis.uoguelph.ca	with users
     mapped to their remote credentials	and root mapped	to the user and	groups
     associated	with ``daemon''; it is exported	to the rest of the world as
     read-only with all	users mapped to	the user and groups associated with
     ``nobody''.

     The file system rooted at /u is exported to all hosts on the subnetwork
     131.104.48	with root mapped to the	UID for	``bin''	and with no group
     access.

     The file system rooted at /u2 is exported to the hosts in ``friends''
     with root mapped to UID and groups	associated with	``root''; it is
     exported to all hosts on network ``cis-net'' allowing mounts at any
     directory within /u2.

     The file system rooted at /a is exported to the network 192.168.0.0, with
     a netmask of 255.255.255.0.  However, the netmask length in the entry for
     /a	is not specified through a -mask option, but through the /prefix nota-
     tion.

     The file system rooted at /a is also exported to the IPv6 network
     3ffe:1ce1:1:fe80::	address, using the upper 64 bits as the	prefix.	 Note
     that, unlike with IPv4 network addresses, the specified network address
     must be complete, and not just contain the	upper bits.  With IPv6
     addresses,	the -mask option must not be used.

     The file system rooted at /cdrom will be exported read-only to the	entire
     network 192.168.33.0/24, including	all its	subdirectories.	 Since /cdrom
     is	the conventional mountpoint for	a CD-ROM device, this export will fail
     if	no CD-ROM medium is currently mounted there since that line would then
     attempt to	export a subdirectory of the root file system with the
     -alldirs option which is not allowed.  The	-quiet option will then	sup-
     press the error message for this condition	that would normally be sys-
     logged.  As soon as an actual CD-ROM is going to be mounted, mount(8)
     will notify mountd(8) about this situation, and the /cdrom	file system
     will be exported as intended.  Note that without using the	-alldirs
     option, the export	would always succeed.  While there is no CD-ROM	medium
     mounted under /cdrom, it would export the (normally empty)	directory
     /cdrom of the root	file system instead.

     The file system rooted at /private	will be	exported using Kerberos	5
     authentication and	will require integrity protected messages for all
     accesses.	The file system	rooted at /secret will also be exported	using
     Kerberos 5	authentication and all messages	used to	access it will be
     encrypted.

     For the experimental server, the NFSv4 tree is rooted at ``/'', and any
     client within the 131.104.48 subnet is permitted to perform NFSv4 state
     operations	on the server, so long as valid	Kerberos credentials are pro-
     vided.  The machine grumpy.cis.uoguelph.ca	is permitted to	perform	NFSv4
     state operations on the server using AUTH_SYS credentials,	as well	as
     Kerberos ones.

SEE ALSO
     netgroup(5), mountd(8), nfsd(8), showmount(8)

BUGS
     The export	options	are tied to the	local mount points in the kernel and
     must be non-contradictory for any exported	subdirectory of	the local
     server mount point.  It is	recommended that all exported directories
     within the	same server file system	be specified on	adjacent lines going
     down the tree.  You cannot	specify	a hostname that	is also	the name of a
     netgroup.	Specifying the full domain specification for a hostname	can
     normally circumvent the problem.

FreeBSD	10.1			 July 12, 2011			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | BUGS

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