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28 .\" @(#)exports.5 8.3 (Berkeley) 3/29/95
36 .Nd define remote mount points for
44 file specifies remote mount points for the
46 mount protocol per the
48 server specification; see
49 .%T "Network File System Protocol Specification" ,
50 RFC1094, Appendix A and
51 .%T "NFS: Network File System Version 3 Specification" ,
55 (other than comment lines that begin with a #)
56 specifies the mount point(s) and export flags within one local server
57 file system or the NFSv4 tree root for one or more hosts.
58 A long line may be split over several lines by ending all but the
59 last line with a backslash
61 A host may be specified only once for each local file or the NFSv4 tree root on the
62 server and there may be only one default entry for each server
63 file system that applies to all other hosts.
64 The latter exports the file system to the
67 be used only when the file system contains public information.
70 the first field(s) specify the directory path(s) within a server file system
71 that can be mounted on by the corresponding client(s).
72 There are three forms of this specification.
73 The first is to list all mount points as absolute
74 directory paths separated by whitespace.
75 This list of directory paths should be considered an
76 .Dq administrative control ,
77 since it is only enforced by the
79 daemon and not the kernel.
80 As such, it only applies to NFSv2 and NFSv3 mounts and only
81 with respect to the client's use of the mount protocol.
82 The second is to specify the pathname of the root of the file system
86 this form allows the host(s) to mount at any point within the file system,
87 including regular files if the
91 Because NFSv4 does not use the mount protocol,
93 .Dq administrative controls
95 Thus, all the above export line(s) should be considered to have the
97 flag, even if the line is specified without it.
98 The third form has the string ``V4:'' followed by a single absolute path
99 name, to specify the NFSv4 tree root.
100 This line does not export any file system, but simply marks where the root
101 of the server's directory tree is for NFSv4 clients.
102 The exported file systems for NFSv4 are specified via the other lines
105 file in the same way as for NFSv2 and NFSv3.
106 The pathnames must not have any symbolic links in them and should not have
112 Mount points for a file system may appear on multiple lines each with
113 different sets of hosts and export options.
115 The second component of a line specifies how the file system is to be
116 exported to the host set.
117 The option flags specify whether the file system
118 is exported read-only or read-write and how the client UID is mapped to
119 user credentials on the server.
120 For the NFSv4 tree root, the only option that can be specified in this
124 Export options are specified as follows:
127 .Fl maproot Li = Sy user
129 The credential of the specified user is used for remote access by root.
130 The credential includes all the groups to which the user is a member
131 on the local machine (see
133 The user may be specified by name or number.
136 .Fl maproot Li = Sy user:group1:group2:...
138 The colon separated list is used to specify the precise credential
139 to be used for remote access by root.
140 The elements of the list may be either names or numbers.
141 Note that user: should be used to distinguish a credential containing
142 no groups from a complete credential for that user.
145 .Fl mapall Li = Sy user
149 .Fl mapall Li = Sy user:group1:group2:...
151 specifies a mapping for all client UIDs (including root)
152 using the same semantics as
159 in an effort to be backward compatible with older export file formats.
165 options, remote accesses by root will result in using a credential of -2:-2.
166 All other users will be mapped to their remote credential.
170 remote access by root will be mapped to that credential instead of -2:-2.
174 all users (including root) will be mapped to that credential in
178 .Fl sec Li = Sy flavor1:flavor2...
180 specifies a colon separated list of acceptable security flavors to be
181 used for remote access.
182 Supported security flavors are sys, krb5, krb5i and krb5p.
183 If multiple flavors are listed, they should be ordered with the most
184 preferred flavor first.
185 If this option is not present,
186 the default security flavor list of just sys is used.
190 option specifies that the file system should be exported read-only
191 (default read/write).
196 in an effort to be backward compatible with older export file formats.
199 exports strictly according to the spec (RFC 2054 and RFC 2055) can
203 However, this flag in itself allows r/w access to all files in
204 the file system, not requiring reserved ports and not remapping UIDs.
206 is only provided to conform to the spec, and should normally not be used.
215 .Fl mapall No = Sy nobody
219 Note that only one file system can be
221 exported on a server.
225 .Fl index No = Pa file
227 option can be used to specify a file whose handle will be returned if
228 a directory is looked up using the public filehandle
230 This is to mimic the behavior of URLs.
233 option is specified, a directory filehandle will be returned as usual.
236 option only makes sense in combination with the
244 option will inhibit some of the syslog diagnostics for bad lines in
246 This can be useful to avoid annoying error messages for known possible
251 The third component of a line specifies the host set to which the line applies.
252 The set may be specified in three ways.
253 The first way is to list the host name(s) separated by white space.
256 addresses may be used in place of names.)
257 The second way is to specify a
263 The third way is to specify an Internet subnetwork using a network and
264 network mask that is defined as the set of all hosts with addresses within
266 This latter approach requires less overhead within the
267 kernel and is recommended for cases where the export line refers to a
268 large number of clients within an administrative subnet.
270 The first two cases are specified by simply listing the name(s) separated
272 All names are checked to see if they are
275 first and are assumed to be hostnames otherwise.
276 Using the full domain specification for a hostname can normally
277 circumvent the problem of a host that has the same name as a netgroup.
278 The third case is specified by the flag
280 .Fl network Li = Sy netname Op Li / Ar prefixlength
284 .Fl mask No = Sy netmask .
286 The netmask may be specified either by attaching a
290 option, or by using a separate
293 If the mask is not specified, it will default to the mask for that network
294 class (A, B or C; see
300 Scoped IPv6 address must carry scope identifier as documented in
310 For the third form which specifies the NFSv4 tree root, the directory path
311 specifies the location within the server's file system tree which is the
312 root of the NFSv4 tree.
313 All entries of this form must specify the same directory path.
314 This location can be any directory and does not
315 need to be within an exported file system. If it is not in an exported
316 file system, a very limited set of operations are permitted, so that an
317 NFSv4 client can traverse the tree to an exported file system.
318 Although parts of the NFSv4 tree can be non-exported, the entire NFSv4 tree
319 must consist of local file systems capable of being exported via NFS.
320 NFSv4 does not use the mount protocol and does permit clients to cross server
321 mount point boundaries, although not all clients are capable of crossing the
326 option on these line(s) specifies what security flavors may be used for
327 NFSv4 operations that do not use file handles. Since these operations
328 (SetClientID, SetClientIDConfirm, Renew, DelegPurge and ReleaseLockOnwer)
329 allocate/modify state in the server, it is possible to restrict some clients to
330 the use of the krb5[ip] security flavors, via this option.
334 This third form is meaningless for NFSv2 and NFSv3 and is ignored for them.
338 utility can be made to re-read the
340 file by sending it a hangup signal as follows:
341 .Bd -literal -offset indent
342 /etc/rc.d/mountd reload
349 output to see whether
351 logged any parsing errors in the
355 .Bl -tag -width /etc/exports -compact
357 the default remote mount-point file
360 .Bd -literal -offset indent
361 /usr /usr/local -maproot=0:10 friends
362 /usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16
363 /usr -ro -mapall=nobody
364 /u -maproot=bin: -network 131.104.48 -mask 255.255.255.0
365 /a -network 192.168.0/24
366 /a -network 3ffe:1ce1:1:fe80::/64
367 /u2 -maproot=root friends
368 /u2 -alldirs -network cis-net -mask cis-mask
369 /cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask 255.255.255.0
372 V4: / -sec=krb5:krb5i:krb5p -network 131.104.48 -mask 255.255.255.0
373 V4: / -sec=sys:krb5:krb5i:krb5p grumpy.cis.uoguelph.ca
381 local file system mount points, the above example specifies the following:
383 The file system rooted at
387 where friends is specified in the netgroup file
388 with users mapped to their remote credentials and
389 root mapped to UID 0 and group 10.
390 It is exported read-write and the hosts in
399 .Em grumpy.cis.uoguelph.ca
400 with users mapped to their remote credentials and
401 root mapped to the user and groups associated with
403 it is exported to the rest of the world as read-only with
404 all users mapped to the user and groups associated with
407 The file system rooted at
409 is exported to all hosts on the subnetwork
411 with root mapped to the UID for
413 and with no group access.
415 The file system rooted at
417 is exported to the hosts in
419 with root mapped to UID and groups
422 it is exported to all hosts on network
424 allowing mounts at any
425 directory within /u2.
427 The file system rooted at
429 is exported to the network 192.168.0.0, with a netmask of 255.255.255.0.
430 However, the netmask length in the entry for
432 is not specified through a
434 option, but through the
438 The file system rooted at
440 is also exported to the IPv6 network
441 .Li 3ffe:1ce1:1:fe80::
442 address, using the upper 64 bits as the prefix.
443 Note that, unlike with IPv4 network addresses, the specified network
444 address must be complete, and not just contain the upper bits.
445 With IPv6 addresses, the
447 option must not be used.
449 The file system rooted at
451 will be exported read-only to the entire network 192.168.33.0/24, including
452 all its subdirectories.
455 is the conventional mountpoint for a CD-ROM device, this export will
456 fail if no CD-ROM medium is currently mounted there since that line
457 would then attempt to export a subdirectory of the root file system
460 option which is not allowed.
463 option will then suppress the error message for this condition that
464 would normally be syslogged.
465 As soon as an actual CD-ROM is going to be mounted,
469 about this situation, and the
471 file system will be exported as intended.
472 Note that without using the
474 option, the export would always succeed.
475 While there is no CD-ROM medium mounted under
477 it would export the (normally empty) directory
479 of the root file system instead.
481 The file system rooted at
483 will be exported using Kerberos 5 authentication and will require
484 integrity protected messages for all accesses.
485 The file system rooted at
487 will also be exported using Kerberos 5 authentication and all messages
488 used to access it will be encrypted.
490 For the experimental server, the NFSv4 tree is rooted at ``/'',
491 and any client within the 131.104.48 subnet is permitted to perform NFSv4 state
492 operations on the server, so long as valid Kerberos credentials are provided.
493 The machine grumpy.cis.uoguelph.ca is permitted to perform NFSv4 state
494 operations on the server using AUTH_SYS credentials, as well as Kerberos ones.
501 The export options are tied to the local mount points in the kernel and
502 must be non-contradictory for any exported subdirectory of the local
504 It is recommended that all exported directories within the same server
505 file system be specified on adjacent lines going down the tree.
506 You cannot specify a hostname that is also the name of a netgroup.
507 Specifying the full domain specification for a hostname can normally
508 circumvent the problem.