1 .\" Copyright (c) 1989, 1991, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
12 .\" 3. Neither the name of the University nor the names of its contributors
13 .\" may be used to endorse or promote products derived from this software
14 .\" without specific prior written permission.
16 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 .Nd define remote mount points for
41 file specifies remote mount points for the
43 mount protocol per the
45 server specification; see
46 .%T "Network File System Protocol Specification" ,
47 RFC1094, Appendix A and
48 .%T "NFS: Network File System Version 3 Specification" ,
52 (other than comment lines that begin with a #)
53 specifies the mount point(s) and export flags within one local server
54 file system or the NFSv4 tree root for one or more hosts.
55 A long line may be split over several lines by ending all but the
56 last line with a backslash
58 A host may be specified only once for each local file or the NFSv4 tree root on the
59 server and there may be only one default entry for each server
60 file system that applies to all other hosts.
61 The latter exports the file system to the
64 be used only when the file system contains public information.
67 the first field(s) specify the directory path(s) within a server file system
68 that can be mounted on by the corresponding client(s).
69 There are three forms of this specification.
70 The first is to list all mount points as absolute
71 directory paths separated by whitespace.
72 This list of directory paths should be considered an
73 .Dq administrative control ,
74 since it is only enforced by the
76 daemon and not the kernel.
77 As such, it only applies to NFSv2 and NFSv3 mounts and only
78 with respect to the client's use of the mount protocol.
79 The second is to specify the pathname of the root of the file system
83 this form allows the host(s) to mount at any point within the file system,
84 including regular files if the
88 Because NFSv4 does not use the mount protocol,
90 .Dq administrative controls
91 are not applied and all directories within this server
92 file system are mountable via NFSv4 even if the
94 flag has not been specified.
95 The third form has the string ``V4:'' followed by a single absolute path
96 name, to specify the NFSv4 tree root.
97 This line does not export any file system, but simply marks where the root
98 of the server's directory tree is for NFSv4 clients.
99 The exported file systems for NFSv4 are specified via the other lines
102 file in the same way as for NFSv2 and NFSv3.
103 The pathnames must not have any symbolic links in them and should not have
109 Pathnames are decoded by
111 allowing special characters to be included in the directory name(s).
112 In particular, whitespace, such as embedded blanks in directory names
114 For example, a blank can be encoded as \(rs040.
118 option may be used to encode directory name(s) with embedded special
120 Mount points for a file system may appear on multiple lines each with
121 different sets of hosts and export options.
123 The second component of a line specifies how the file system is to be
124 exported to the host set.
125 The option flags specify whether the file system
126 is exported read-only or read-write and how the client UID is mapped to
127 user credentials on the server.
128 For the NFSv4 tree root, the only options that can be specified in this
129 section are ones related to security:
136 Export options are specified as follows:
139 .Fl maproot Li = Sy user
141 The credential of the specified user is used for remote access by root.
142 The credential includes all the groups to which the user is a member
143 on the local machine (see
145 The user may be specified by name or number.
146 The user string may be quoted, or use backslash escaping.
149 .Fl maproot Li = Sy user:group1:group2:...
151 The colon separated list is used to specify the precise credential
152 to be used for remote access by root.
153 The elements of the list may be either names or numbers.
154 Note that user: should be used to distinguish a credential containing
155 no groups from a complete credential for that user.
156 The group names may be quoted, or use backslash escaping.
159 .Fl mapall Li = Sy user
163 .Fl mapall Li = Sy user:group1:group2:...
165 specifies a mapping for all client UIDs (including root)
166 using the same semantics as
173 in an effort to be backward compatible with older export file formats.
179 options, remote accesses by root will result in using a credential of 65534:65533.
180 All other users will be mapped to their remote credential.
184 remote access by root will be mapped to that credential instead of 65534:65533.
188 all users (including root) will be mapped to that credential in
192 .Fl sec Li = Sy flavor1:flavor2...
194 specifies a colon separated list of acceptable security flavors to be
195 used for remote access.
196 Supported security flavors are sys, krb5, krb5i and krb5p.
197 If multiple flavors are listed, they should be ordered with the most
198 preferred flavor first.
199 If this option is not present,
200 the default security flavor list of just sys is used.
204 option specifies that the file system should be exported read-only
205 (default read/write).
210 in an effort to be backward compatible with older export file formats.
213 exports strictly according to the spec (RFC 2054 and RFC 2055) can
217 However, this flag in itself allows r/w access to all files in
218 the file system, not requiring reserved ports and not remapping UIDs.
220 is only provided to conform to the spec, and should normally not be used.
229 .Fl mapall No = Sy nobody
233 Note that only one file system can be
235 exported on a server.
239 .Fl index No = Pa file
241 option can be used to specify a file whose handle will be returned if
242 a directory is looked up using the public filehandle
244 This is to mimic the behavior of URLs.
247 option is specified, a directory filehandle will be returned as usual.
250 option only makes sense in combination with the
261 export options are used to require the client to use TLS for the mount(s)
263 For NFS mounts using TLS to work,
265 must be running on the server.
266 .Bd -filled -offset indent
268 requires that the client use TLS.
271 requires that the client use TLS and provide a verifiable X.509 certificate
272 during TLS handshake.
275 requires that the client use TLS and provide a verifiable X.509 certificate.
276 The otherName component of the certificate's subjAltName must have a
277 an OID of 1.3.6.1.4.1.2238.1.1.1 and a UTF8 string of the form
280 will be translated to the credentials of the specified user in the same
285 is normally a username is the server's password database and
287 is the DNS domain name for the server.
288 All RPCs will be performed using these credentials instead of the
289 ones in the RPC header in a manner similar to
291 .Fl mapall Li = Sy user .
295 If none of these three flags are specified, TLS mounts are permitted but
300 option will inhibit some of the syslog diagnostics for bad lines in
302 This can be useful to avoid annoying error messages for known possible
307 The third component of a line specifies the host set to which the line applies.
308 The set may be specified in three ways.
309 The first way is to list the host name(s) separated by white space.
312 addresses may be used in place of names.)
313 The second way is to specify a
319 The third way is to specify an Internet subnetwork using a network and
320 network mask that is defined as the set of all hosts with addresses within
322 This latter approach requires less overhead within the
323 kernel and is recommended for cases where the export line refers to a
324 large number of clients within an administrative subnet.
326 The first two cases are specified by simply listing the name(s) separated
328 All names are checked to see if they are
331 first and are assumed to be hostnames otherwise.
332 Using the full domain specification for a hostname can normally
333 circumvent the problem of a host that has the same name as a netgroup.
334 The third case is specified by the flag
336 .Fl network Li = Sy netname Op Li / Ar prefixlength
340 .Fl mask No = Sy netmask .
342 The netmask may be specified either by attaching a
346 option, or by using a separate
349 If the mask is not specified, it will default to the historical mask
350 for that network class (A, B, or C; see
352 This usage is deprecated, and will elicit a warning log message.
357 Scoped IPv6 address must carry scope identifier as documented in
367 For the third form which specifies the NFSv4 tree root, the directory path
368 specifies the location within the server's file system tree which is the
369 root of the NFSv4 tree.
370 There can only be one NFSv4 root directory per server.
371 As such, all entries of this form must specify the same directory path.
372 For file systems other than ZFS,
373 this location can be any directory and does not
374 need to be within an exported file system.
375 If it is not in an exported file system, a very limited set of operations
376 are permitted, so that an NFSv4 client can traverse the tree to an
377 exported file system.
378 Although parts of the NFSv4 tree can be non-exported, the entire NFSv4 tree
379 must consist of local file systems capable of being exported via NFS.
380 All ZFS file systems in the subtree below the NFSv4 tree root must be
382 NFSv4 does not use the mount protocol and does permit clients to cross server
383 mount point boundaries, although not all clients are capable of crossing the
388 option on these line(s) specifies what security flavors may be used for
389 NFSv4 operations that do not use file handles.
390 Since these operations (SetClientID, SetClientIDConfirm, Renew, DelegPurge
391 and ReleaseLockOnwer) allocate/modify state in the server, it is possible
392 to restrict some clients to the use of the krb5[ip] security flavors,
397 This third form is meaningless for NFSv2 and NFSv3 and is ignored for them.
401 utility can be made to re-read the
403 file by sending it a hangup signal as follows:
404 .Bd -literal -offset indent
405 /etc/rc.d/mountd reload
412 output to see whether
414 logged any parsing errors in the
418 .Bl -tag -width /etc/exports -compact
420 the default remote mount-point file
428 local file system mount points, let's consider the following example:
430 .Bd -literal -offset indent
431 /usr /usr/local -maproot=0:10 friends
432 /usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16
433 /usr -ro -mapall=nobody
434 /u -maproot=bin: -network 131.104.48 -mask 255.255.255.0
435 /a -network 192.168.0/24
436 /a -network 3ffe:1ce1:1:fe80::/64
437 /u2 -maproot=root friends
438 /u2 -alldirs -network cis-net -mask cis-mask
439 /cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask 255.255.255.0
442 V4: / -sec=krb5:krb5i:krb5p -network 131.104.48 -mask 255.255.255.0
443 V4: / -sec=sys:krb5:krb5i:krb5p grumpy.cis.uoguelph.ca
446 The file systems rooted at
450 are exported to hosts within the
453 with users mapped to their remote credentials and
454 root mapped to UID 0 and group 10.
455 They are exported read-write and the hosts in
458 The file system rooted at
463 .Em grumpy.cis.uoguelph.ca
464 with users mapped to their remote credentials and
465 root mapped to the user and groups associated with
467 it is exported to the rest of the world as read-only with
468 all users mapped to the user and groups associated with
471 The file system rooted at
473 is exported to all hosts on the subnetwork
475 with root mapped to the UID for
477 and with no group access.
479 The file system rooted at
481 is exported to the hosts in
483 with root mapped to UID and groups
486 it is exported to all hosts on network
488 allowing mounts at any
489 directory within /u2.
491 The file system rooted at
493 is exported to the network 192.168.0.0, with a netmask of 255.255.255.0.
494 However, the netmask length in the entry for
496 is not specified through a
498 option, but through the
502 The file system rooted at
504 is also exported to the IPv6 network
505 .Li 3ffe:1ce1:1:fe80::
506 address, using the upper 64 bits as the prefix.
507 Note that, unlike with IPv4 network addresses, the specified network
508 address must be complete, and not just contain the upper bits.
509 With IPv6 addresses, the
511 option must not be used.
513 The file system rooted at
515 will be exported read-only to the entire network 192.168.33.0/24, including
516 all its subdirectories.
519 is the conventional mountpoint for a CD-ROM device, this export will
520 fail if no CD-ROM medium is currently mounted there since that line
521 would then attempt to export a subdirectory of the root file system
524 option which is not allowed.
527 option will then suppress the error message for this condition that
528 would normally be syslogged.
529 As soon as an actual CD-ROM is going to be mounted,
533 about this situation, and the
535 file system will be exported as intended.
536 Note that without using the
538 option, the export would always succeed.
539 While there is no CD-ROM medium mounted under
541 it would export the (normally empty) directory
543 of the root file system instead.
545 The file system rooted at
547 will be exported using Kerberos 5 authentication and will require
548 integrity protected messages for all accesses.
549 The file system rooted at
551 will also be exported using Kerberos 5 authentication and all messages
552 used to access it will be encrypted.
554 For the experimental server, the NFSv4 tree is rooted at ``/'',
555 and any client within the 131.104.48 subnet is permitted to perform NFSv4 state
556 operations on the server, so long as valid Kerberos credentials are provided.
557 The machine grumpy.cis.uoguelph.ca is permitted to perform NFSv4 state
558 operations on the server using AUTH_SYS credentials, as well as Kerberos ones.
560 In the following example some directories are exported as NFSv3 and NFSv4:
561 .Bd -literal -offset indent
563 /wingsdl/nfsv4/usr-ports -maproot=root -network 172.16.0.0 -mask 255.255.0.0
564 /wingsdl/nfsv4/clasper -maproot=root clasper
567 Only one V4: line is needed or allowed to declare where NFSv4 is
569 The other lines declare specific exported directories with
570 their absolute paths given in /etc/exports.
572 The exported directories' paths are used for both v3 and v4.
573 However, they are interpreted differently for v3 and v4.
574 A client mount command for usr-ports would use the server-absolute name when
576 .Bd -literal -offset indent
577 mount server:/wingsdl/nfsv4/usr-ports /mnt/tmp
580 A mount command using NFSv4 would use the path relative to the NFSv4
582 .Bd -literal -offset indent
583 mount server:/usr-ports /mnt/tmp
586 This also differentiates which version you want if the client can do
588 The former will only ever do a v3 mount and the latter will only ever
591 Note that due to different mount behavior between NFSv3 and NFSv4 a
592 NFSv4 mount request for a directory that the client does not have
593 permission for will succeed and read/write access will fail
594 afterwards, whereas NFSv3 rejects the mount request.
605 The implementation is based on the following documents:
609 .%T "Network File System Protocol Specification, Appendix A, RFC 1094"
613 .%T "NFS: Network File System Version 3, Appendix I, RFC 1813"
617 .%T "Towards Remote Procedure Call Encryption By Default, RFC nnnn"
621 The export options are tied to the local mount points in the kernel and
622 must be non-contradictory for any exported subdirectory of the local
624 It is recommended that all exported directories within the same server
625 file system be specified on adjacent lines going down the tree.
626 You cannot specify a hostname that is also the name of a netgroup.
627 Specifying the full domain specification for a hostname can normally
628 circumvent the problem.