1.\" Copyright (c) 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 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. 15.\" 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 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)exports.5 8.3 (Berkeley) 3/29/95 29.\" $FreeBSD: src/sbin/mountd/exports.5,v 1.10.2.8 2002/09/28 16:31:45 markm Exp $ 30.\" $DragonFly: src/sbin/mountd/exports.5,v 1.5 2007/11/23 23:16:36 swildner Exp $ 31.\" 32.Dd March 29, 1995 33.Dt EXPORTS 5 34.Os 35.Sh NAME 36.Nm exports 37.Nd define remote mount points for 38.Tn NFS 39mount requests 40.Sh SYNOPSIS 41.Nm 42.Sh DESCRIPTION 43The 44.Nm 45file specifies remote mount points for the 46.Tn NFS 47mount protocol per the 48.Tn NFS 49server specification; see 50.%T "Network File System Protocol Specification" , 51RFC 1094, Appendix A and 52.%T "NFS: Network File System Version 3 Specification" , 53Appendix I. 54.Pp 55Each line in the file 56(other than comment lines that begin with a #) 57specifies the mount point(s) and export flags within one local server 58filesystem for one or more hosts. 59A host may be specified only once for each local filesystem on the 60server and there may be only one default entry for each server 61filesystem that applies to all other hosts. 62The latter exports the filesystem to the ``world'' and should 63be used only when the filesystem contains public information. 64.Pp 65In a mount entry, 66the first field(s) specify the directory path(s) within a server filesystem 67that can be mounted on by the corresponding client(s). 68There are two forms of this specification. 69The first is to list all mount points as absolute 70directory paths separated by whitespace. 71The second is to specify the pathname of the root of the filesystem 72followed by the 73.Fl alldirs 74flag; 75this form allows the host(s) to mount at any point within the filesystem, 76including regular files if the 77.Fl r 78option is used on 79.Xr mountd 8 . 80The pathnames must not have any symbolic links in them and should not have 81any "." or ".." components. 82Mount points for a filesystem may appear on multiple lines each with 83different sets of hosts and export options. 84.Pp 85The second component of a line specifies how the filesystem is to be 86exported to the host set. 87The option flags specify whether the filesystem 88is exported read-only or read-write and how the client uid is mapped to 89user credentials on the server. 90.Pp 91Export options are specified as follows: 92.Pp 93.Sm off 94.Fl maproot No = Sy user 95.Sm on 96The credential of the specified user is used for remote access by root. 97The credential includes all the groups to which the user is a member 98on the local machine (see 99.Xr id 1 ) . 100The user may be specified by name or number. 101.Pp 102.Sm off 103.Fl maproot No = Sy user:group1:group2:... 104.Sm on 105The colon separated list is used to specify the precise credential 106to be used for remote access by root. 107The elements of the list may be either names or numbers. 108Note that user: should be used to distinguish a credential containing 109no groups from a complete credential for that user. 110.Pp 111.Sm off 112.Fl mapall No = Sy user 113.Sm on 114or 115.Sm off 116.Fl mapall No = Sy user:group1:group2:... 117.Sm on 118specifies a mapping for all client uids (including root) 119using the same semantics as 120.Fl maproot . 121.Pp 122The option 123.Fl r 124is a synonym for 125.Fl maproot 126in an effort to be backward compatible with older export file formats. 127.Pp 128In the absence of 129.Fl maproot 130and 131.Fl mapall 132options, remote accesses by root will result in using a credential of -2:-2. 133All other users will be mapped to their remote credential. 134If a 135.Fl maproot 136option is given, 137remote access by root will be mapped to that credential instead of -2:-2. 138If a 139.Fl mapall 140option is given, 141all users (including root) will be mapped to that credential in 142place of their own. 143.Pp 144The 145.Fl ro 146option specifies that the filesystem should be exported read-only 147(default read/write). 148The option 149.Fl o 150is a synonym for 151.Fl ro 152in an effort to be backward compatible with older export file formats. 153.Pp 154.Tn WebNFS 155exports strictly according to the spec (RFC 2054 and RFC 2055) can 156be done with the 157.Fl public 158flag. 159However, this flag in itself allows r/w access to all files in 160the filesystem, not requiring reserved ports and not remapping uids. 161It 162is only provided to conform to the spec, and should normally not be used. 163For a 164.Tn WebNFS 165export, 166use the 167.Fl webnfs 168flag, which implies 169.Fl public , 170.Sm off 171.Fl mapall No = Sy nobody 172.Sm on 173and 174.Fl ro . 175.Pp 176A 177.Sm off 178.Fl index No = Sy file 179.Sm on 180option can be used to specify a file whose handle will be returned if 181a directory is looked up using the public filehandle 182.Pq Tn WebNFS . 183This is to mimic the behavior of URLs. 184If no 185.Fl index 186option is specified, a directory filehandle will be returned as usual. 187The 188.Fl index 189option only makes sense in combination with the 190.Fl public 191or 192.Fl webnfs 193flags. 194.Pp 195Specifying the 196.Fl quiet 197option will inhibit some of the syslog diagnostics for bad lines in 198.Pa /etc/exports . 199This can be useful to avoid annoying error messages for known possible 200problems (see 201.Sx EXAMPLES 202below). 203.Pp 204The third component of a line specifies the host set to which the line applies. 205The set may be specified in three ways. 206The first way is to list the host name(s) separated by white space. 207(Standard Internet ``dot'' addresses may be used in place of names.) 208The second way is to specify a ``netgroup'' as defined in the netgroup file (see 209.Xr netgroup 5 ) . 210The third way is to specify an Internet subnetwork using a network and 211network mask that is defined as the set of all hosts with addresses within 212the subnetwork. 213This latter approach requires less overhead within the 214kernel and is recommended for cases where the export line refers to a 215large number of clients within an administrative subnet. 216.Pp 217The first two cases are specified by simply listing the name(s) separated 218by whitespace. 219All names are checked to see if they are ``netgroup'' names 220first and are assumed to be hostnames otherwise. 221Using the full domain specification for a hostname can normally 222circumvent the problem of a host that has the same name as a netgroup. 223The third case is specified by the flag 224.Sm off 225.Fl network No = Sy netname 226.Sm on 227and optionally 228.Sm off 229.Fl mask No = Sy netmask . 230.Sm on 231If the mask is not specified, it will default to the mask for that network 232class (A, B or C; see 233.Xr inet 4 ) . 234See the 235.Sx EXAMPLES 236section below. 237.Pp 238The 239.Xr mountd 8 240utility can be made to re-read the 241.Nm 242file by sending it a hangup signal as follows: 243.Bd -literal -offset indent 244kill -s HUP `cat /var/run/mountd.pid` 245.Ed 246.Pp 247After sending the 248.Dv SIGHUP , 249check the 250.Xr syslogd 8 251output to see whether 252.Xr mountd 8 253logged any parsing errors in the 254.Nm 255file. 256.Sh FILES 257.Bl -tag -width /etc/exports -compact 258.It Pa /etc/exports 259the default remote mount-point file 260.El 261.Sh EXAMPLES 262.Bd -literal -offset indent 263/usr /usr/local -maproot=0:10 friends 264/usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16 265/usr -ro -mapall=nobody 266/u -maproot=bin: -network 131.104.48 -mask 255.255.255.0 267/u2 -maproot=root friends 268/u2 -alldirs -network cis-net -mask cis-mask 269/cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask 255.255.255.0 270.Ed 271.Pp 272Given that 273.Pa /usr , 274.Pa /u 275and 276.Pa /u2 277are 278local filesystem mount points, the above example specifies the following: 279.Pa /usr 280is exported to hosts 281.Em friends 282where friends is specified in the netgroup file 283with users mapped to their remote credentials and 284root mapped to uid 0 and group 10. 285It is exported read-write and the hosts in ``friends'' can mount either /usr 286or /usr/local. 287It is exported to 288.Em 131.104.48.16 289and 290.Em grumpy.cis.uoguelph.ca 291with users mapped to their remote credentials and 292root mapped to the user and groups associated with ``daemon''; 293it is exported to the rest of the world as read-only with 294all users mapped to the user and groups associated with ``nobody''. 295.Pp 296.Pa /u 297is exported to all hosts on the subnetwork 298.Em 131.104.48 299with root mapped to the uid for ``bin'' and with no group access. 300.Pp 301.Pa /u2 302is exported to the hosts in ``friends'' with root mapped to uid and groups 303associated with ``root''; 304it is exported to all hosts on network ``cis-net'' allowing mounts at any 305directory within /u2. 306.Pp 307The filesystem rooted at 308.Pa /cdrom 309will exported read-only to the entire network 192.168.33.0/24, including 310all its subdirectories. 311Since 312.Pa /cdrom 313is the conventional mountpoint for a CD-ROM device, this export will 314fail if no CD-ROM medium is currently mounted there since that line 315would then attempt to export a subdirectory of the root filesystem 316with the 317.Fl alldirs 318option which is not allowed. 319The 320.Fl quiet 321option will then suppress the error message for this condition that 322would normally be syslogged. 323As soon as an actual CD-ROM is going to be mounted, 324.Xr mount 8 325will notify 326.Xr mountd 8 327about this situation, and the 328.Pa /cdrom 329filesystem will be exported as intended. 330Note that without using the 331.Fl alldirs 332option, the export would always succeed. 333While there is no CD-ROM medium mounted under 334.Pa /cdrom , 335it would export the (normally empty) directory 336.Pa /cdrom 337of the root filesystem instead. 338.Sh SEE ALSO 339.Xr netgroup 5 , 340.Xr mountd 8 , 341.Xr nfsd 8 , 342.Xr showmount 8 343.Sh BUGS 344The export options are tied to the local mount points in the kernel and 345must be non-contradictory for any exported subdirectory of the local 346server mount point. 347It is recommended that all exported directories within the same server 348filesystem be specified on adjacent lines going down the tree. 349You cannot specify a hostname that is also the name of a netgroup. 350Specifying the full domain specification for a hostname can normally 351circumvent the problem. 352