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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 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 system 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 two forms of this specification.
73 The first is to list all mount points as absolute
74 directory paths separated by whitespace.
75 The second is to specify the pathname of the root of the file system
79 this form allows the host(s) to mount at any point within the file system,
80 including regular files if the
84 The pathnames must not have any symbolic links in them and should not have
90 Mount points for a file system may appear on multiple lines each with
91 different sets of hosts and export options.
93 The second component of a line specifies how the file system is to be
94 exported to the host set.
95 The option flags specify whether the file system
96 is exported read-only or read-write and how the client UID is mapped to
97 user credentials on the server.
99 Export options are specified as follows:
102 .Fl maproot Li = Sy user
104 The credential of the specified user is used for remote access by root.
105 The credential includes all the groups to which the user is a member
106 on the local machine (see
108 The user may be specified by name or number.
111 .Fl maproot Li = Sy user:group1:group2:...
113 The colon separated list is used to specify the precise credential
114 to be used for remote access by root.
115 The elements of the list may be either names or numbers.
116 Note that user: should be used to distinguish a credential containing
117 no groups from a complete credential for that user.
120 .Fl mapall Li = Sy user
124 .Fl mapall Li = Sy user:group1:group2:...
126 specifies a mapping for all client UIDs (including root)
127 using the same semantics as
134 in an effort to be backward compatible with older export file formats.
140 options, remote accesses by root will result in using a credential of -2:-2.
141 All other users will be mapped to their remote credential.
145 remote access by root will be mapped to that credential instead of -2:-2.
149 all users (including root) will be mapped to that credential in
154 option specifies that the file system should be exported read-only
155 (default read/write).
160 in an effort to be backward compatible with older export file formats.
163 exports strictly according to the spec (RFC 2054 and RFC 2055) can
167 However, this flag in itself allows r/w access to all files in
168 the file system, not requiring reserved ports and not remapping UIDs.
170 is only provided to conform to the spec, and should normally not be used.
179 .Fl mapall No = Sy nobody
183 Note that only one file system can be
185 exported on a server.
189 .Fl index No = Pa file
191 option can be used to specify a file whose handle will be returned if
192 a directory is looked up using the public filehandle
194 This is to mimic the behavior of URLs.
197 option is specified, a directory filehandle will be returned as usual.
200 option only makes sense in combination with the
208 option will inhibit some of the syslog diagnostics for bad lines in
210 This can be useful to avoid annoying error messages for known possible
215 The third component of a line specifies the host set to which the line applies.
216 The set may be specified in three ways.
217 The first way is to list the host name(s) separated by white space.
220 addresses may be used in place of names.)
221 The second way is to specify a
227 The third way is to specify an Internet subnetwork using a network and
228 network mask that is defined as the set of all hosts with addresses within
230 This latter approach requires less overhead within the
231 kernel and is recommended for cases where the export line refers to a
232 large number of clients within an administrative subnet.
234 The first two cases are specified by simply listing the name(s) separated
236 All names are checked to see if they are
239 first and are assumed to be hostnames otherwise.
240 Using the full domain specification for a hostname can normally
241 circumvent the problem of a host that has the same name as a netgroup.
242 The third case is specified by the flag
244 .Fl network Li = Sy netname Op Li / Ar prefixlength
248 .Fl mask No = Sy netmask .
250 The netmask may be specified either by attaching a
254 option, or by using a separate
257 If the mask is not specified, it will default to the mask for that network
258 class (A, B or C; see
264 Scoped IPv6 address must carry scope identifier as documented in
276 utility can be made to re-read the
278 file by sending it a hangup signal as follows:
279 .Bd -literal -offset indent
280 /etc/rc.d/mountd reload
287 output to see whether
289 logged any parsing errors in the
293 .Bl -tag -width /etc/exports -compact
295 the default remote mount-point file
298 .Bd -literal -offset indent
299 /usr /usr/local -maproot=0:10 friends
300 /usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16
301 /usr -ro -mapall=nobody
302 /u -maproot=bin: -network 131.104.48 -mask 255.255.255.0
303 /a -network 192.168.0/24
304 /a -network 3ffe:1ce1:1:fe80::/64
305 /u2 -maproot=root friends
306 /u2 -alldirs -network cis-net -mask cis-mask
307 /cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask 255.255.255.0
315 local file system mount points, the above example specifies the following:
317 The file system rooted at
321 where friends is specified in the netgroup file
322 with users mapped to their remote credentials and
323 root mapped to UID 0 and group 10.
324 It is exported read-write and the hosts in
333 .Em grumpy.cis.uoguelph.ca
334 with users mapped to their remote credentials and
335 root mapped to the user and groups associated with
337 it is exported to the rest of the world as read-only with
338 all users mapped to the user and groups associated with
341 The file system rooted at
343 is exported to all hosts on the subnetwork
345 with root mapped to the UID for
347 and with no group access.
349 The file system rooted at
351 is exported to the hosts in
353 with root mapped to UID and groups
356 it is exported to all hosts on network
358 allowing mounts at any
359 directory within /u2.
361 The file system rooted at
363 is exported to the network 192.168.0.0, with a netmask of 255.255.255.0.
364 However, the netmask length in the entry for
366 is not specified through a
368 option, but through the
372 The file system rooted at
374 is also exported to the IPv6 network
375 .Li 3ffe:1ce1:1:fe80::
376 address, using the upper 64 bits as the prefix.
377 Note that, unlike with IPv4 network addresses, the specified network
378 address must be complete, and not just contain the upper bits.
379 With IPv6 addresses, the
381 option must not be used.
383 The file system rooted at
385 will be exported read-only to the entire network 192.168.33.0/24, including
386 all its subdirectories.
389 is the conventional mountpoint for a CD-ROM device, this export will
390 fail if no CD-ROM medium is currently mounted there since that line
391 would then attempt to export a subdirectory of the root file system
394 option which is not allowed.
397 option will then suppress the error message for this condition that
398 would normally be syslogged.
399 As soon as an actual CD-ROM is going to be mounted,
403 about this situation, and the
405 file system will be exported as intended.
406 Note that without using the
408 option, the export would always succeed.
409 While there is no CD-ROM medium mounted under
411 it would export the (normally empty) directory
413 of the root file system instead.
420 The export options are tied to the local mount points in the kernel and
421 must be non-contradictory for any exported subdirectory of the local
423 It is recommended that all exported directories within the same server
424 file system be specified on adjacent lines going down the tree.
425 You cannot specify a hostname that is also the name of a netgroup.
426 Specifying the full domain specification for a hostname can normally
427 circumvent the problem.