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32 .\" @(#)exports.5 8.3 (Berkeley) 3/29/95
33 .\" $FreeBSD: src/sbin/mountd/exports.5,v 1.10.2.8 2002/09/28 16:31:45 markm Exp $
40 .Nd define remote mount points for
48 file specifies remote mount points for the
50 mount protocol per the
52 server specification; see
53 .%T "Network File System Protocol Specification" ,
54 RFC1094, Appendix A and
55 .%T "NFS: Network File System Version 3 Specification" ,
59 (other than comment lines that begin with a #)
60 specifies the mount point(s) and export flags within one local server
61 filesystem for one or more hosts.
62 A host may be specified only once for each local filesystem on the
63 server and there may be only one default entry for each server
64 filesystem that applies to all other hosts.
65 The latter exports the filesystem to the ``world'' and should
66 be used only when the filesystem contains public information.
69 the first field(s) specify the directory path(s) within a server filesystem
70 that can be mounted on by the corresponding client(s).
71 There are two forms of this specification.
72 The first is to list all mount points as absolute
73 directory paths separated by whitespace.
74 The second is to specify the pathname of the root of the filesystem
78 this form allows the host(s) to mount at any point within the filesystem,
79 including regular files if the
83 The pathnames must not have any symbolic links in them and should not have
84 any "." or ".." components.
85 Mount points for a filesystem may appear on multiple lines each with
86 different sets of hosts and export options.
88 The second component of a line specifies how the filesystem is to be
89 exported to the host set.
90 The option flags specify whether the filesystem
91 is exported read-only or read-write and how the client uid is mapped to
92 user credentials on the server.
94 Export options are specified as follows:
97 .Fl maproot No = Sy user
99 The credential of the specified user is used for remote access by root.
100 The credential includes all the groups to which the user is a member
101 on the local machine (see
103 The user may be specified by name or number.
106 .Fl maproot No = Sy user:group1:group2:...
108 The colon separated list is used to specify the precise credential
109 to be used for remote access by root.
110 The elements of the list may be either names or numbers.
111 Note that user: should be used to distinguish a credential containing
112 no groups from a complete credential for that user.
115 .Fl mapall No = Sy user
119 .Fl mapall No = Sy user:group1:group2:...
121 specifies a mapping for all client uids (including root)
122 using the same semantics as
129 in an effort to be backward compatible with older export file formats.
135 options, remote accesses by root will result in using a credential of -2:-2.
136 All other users will be mapped to their remote credential.
140 remote access by root will be mapped to that credential instead of -2:-2.
144 all users (including root) will be mapped to that credential in
149 option specifies that the filesystem should be exported read-only
150 (default read/write).
155 in an effort to be backward compatible with older export file formats.
158 exports strictly according to the spec (RFC 2054 and RFC 2055) can
162 However, this flag in itself allows r/w access to all files in
163 the filesystem, not requiring reserved ports and not remapping uids.
165 is only provided to conform to the spec, and should normally not be used.
174 .Fl mapall No = Sy nobody
181 .Fl index No = Sy file
183 option can be used to specify a file whose handle will be returned if
184 a directory is looked up using the public filehandle
186 This is to mimic the behavior of URLs.
189 option is specified, a directory filehandle will be returned as usual.
192 option only makes sense in combination with the
200 option will inhibit some of the syslog diagnostics for bad lines in
202 This can be useful to avoid annoying error messages for known possible
207 The third component of a line specifies the host set to which the line applies.
208 The set may be specified in three ways.
209 The first way is to list the host name(s) separated by white space.
210 (Standard Internet ``dot'' addresses may be used in place of names.)
211 The second way is to specify a ``netgroup'' as defined in the netgroup file (see
213 The third way is to specify an Internet subnetwork using a network and
214 network mask that is defined as the set of all hosts with addresses within
216 This latter approach requires less overhead within the
217 kernel and is recommended for cases where the export line refers to a
218 large number of clients within an administrative subnet.
220 The first two cases are specified by simply listing the name(s) separated
222 All names are checked to see if they are ``netgroup'' names
223 first and are assumed to be hostnames otherwise.
224 Using the full domain specification for a hostname can normally
225 circumvent the problem of a host that has the same name as a netgroup.
226 The third case is specified by the flag
228 .Fl network No = Sy netname
232 .Fl mask No = Sy netmask .
234 If the mask is not specified, it will default to the mask for that network
235 class (A, B or C; see
243 utility can be made to re-read the
245 file by sending it a hangup signal as follows:
246 .Bd -literal -offset indent
247 kill -s HUP `cat /var/run/mountd.pid`
254 output to see whether
256 logged any parsing errors in the
260 .Bl -tag -width /etc/exports -compact
262 the default remote mount-point file
265 .Bd -literal -offset indent
266 /usr /usr/local -maproot=0:10 friends
267 /usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16
268 /usr -ro -mapall=nobody
269 /u -maproot=bin: -network 131.104.48 -mask 255.255.255.0
270 /u2 -maproot=root friends
271 /u2 -alldirs -network cis-net -mask cis-mask
272 /cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask 255.255.255.0
281 local filesystem mount points, the above example specifies the following:
285 where friends is specified in the netgroup file
286 with users mapped to their remote credentials and
287 root mapped to uid 0 and group 10.
288 It is exported read-write and the hosts in ``friends'' can mount either /usr
293 .Em grumpy.cis.uoguelph.ca
294 with users mapped to their remote credentials and
295 root mapped to the user and groups associated with ``daemon'';
296 it is exported to the rest of the world as read-only with
297 all users mapped to the user and groups associated with ``nobody''.
300 is exported to all hosts on the subnetwork
302 with root mapped to the uid for ``bin'' and with no group access.
305 is exported to the hosts in ``friends'' with root mapped to uid and groups
306 associated with ``root'';
307 it is exported to all hosts on network ``cis-net'' allowing mounts at any
308 directory within /u2.
310 The filesystem rooted at
312 will exported read-only to the entire network 192.168.33.0/24, including
313 all its subdirectories.
316 is the conventional mountpoint for a CD-ROM device, this export will
317 fail if no CD-ROM medium is currently mounted there since that line
318 would then attempt to export a subdirectory of the root filesystem
321 option which is not allowed.
324 option will then suppress the error message for this condition that
325 would normally be syslogged.
326 As soon as an actual CD-ROM is going to be mounted,
330 about this situation, and the
332 filesystem will be exported as intented.
333 Note that without using the
335 option, the export would always succeed.
336 While there is no CD-ROM medium mounted under
338 it would export the (normally empty) directory
340 of the root filesystem instead.
347 The export options are tied to the local mount points in the kernel and
348 must be non-contradictory for any exported subdirectory of the local
350 It is recommended that all exported directories within the same server
351 filesystem be specified on adjacent lines going down the tree.
352 You cannot specify a hostname that is also the name of a netgroup.
353 Specifying the full domain specification for a hostname can normally
354 circumvent the problem.