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32 .\" @(#)exports.5 8.3 (Berkeley) 3/29/95
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 Kerberos authentication server should be
150 used to authenticate and map client credentials.
151 This option requires that the kernel be built with the NFSKERB option.
152 The use of this option will prevent the kernel from compiling
153 unless calls to the appropriate Kerberos encryption routines
154 are provided in the NFS source.
158 option specifies that the filesystem should be exported read-only
159 (default read/write).
164 in an effort to be backward compatible with older export file formats.
167 exports strictly according to the spec (RFC 2054 and RFC 2055) can
171 However, this flag in itself allows r/w access to all files in
172 the filesystem, not requiring reserved ports and not remapping uids.
174 is only provided to conform to the spec, and should normally not be used.
183 .Fl mapall No = Sy nobody
190 .Fl index No = Sy file
192 option can be used to specify a file whose handle will be returned if
193 a directory is looked up using the public filehandle (
195 This is to mimic the behavior of URLs.
198 option is specified, a directory filehandle will be returned as usual.
201 option only makes sense in combination with the
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
239 .Bd -literal -offset indent
240 /usr /usr/local -maproot=0:10 friends
241 /usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16
242 /usr -ro -mapall=nobody
243 /u -maproot=bin: -network 131.104.48 -mask 255.255.255.0
244 /u2 -maproot=root friends
245 /u2 -alldirs -kerb -network cis-net -mask cis-mask
254 local filesystem mount points, the above example specifies the following:
258 where friends is specified in the netgroup file
259 with users mapped to their remote credentials and
260 root mapped to uid 0 and group 10.
261 It is exported read-write and the hosts in ``friends'' can mount either /usr
266 .Em grumpy.cis.uoguelph.ca
267 with users mapped to their remote credentials and
268 root mapped to the user and groups associated with ``daemon'';
269 it is exported to the rest of the world as read-only with
270 all users mapped to the user and groups associated with ``nobody''.
273 is exported to all hosts on the subnetwork
275 with root mapped to the uid for ``bin'' and with no group access.
278 is exported to the hosts in ``friends'' with root mapped to uid and groups
279 associated with ``root'';
280 it is exported to all hosts on network ``cis-net'' allowing mounts at any
281 directory within /u2 and mapping all uids to credentials for the principal
282 that is authenticated by a Kerberos ticket.
286 utility can be made to re-read the
288 file by sending it a hangup signal as follows:
289 .Bd -literal -offset indent
290 kill -s HUP `cat /var/run/mountd.pid`
297 output to see whether
299 logged any parsing errors in the
303 .Bl -tag -width /etc/exports -compact
305 the default remote mount-point file
313 The export options are tied to the local mount points in the kernel and
314 must be non-contradictory for any exported subdirectory of the local
316 It is recommended that all exported directories within the same server
317 filesystem be specified on adjacent lines going down the tree.
318 You cannot specify a hostname that is also the name of a netgroup.
319 Specifying the full domain specification for a hostname can normally
320 circumvent the problem.