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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)exports.5 8.3 (Berkeley) 3/29/95 33.\" $FreeBSD$ 34.\" 35.Dd March 29, 1995 36.Dt EXPORTS 5 37.Os 38.Sh NAME 39.Nm exports 40.Nd define remote mount points for 41.Tn NFS 42mount requests 43.Sh SYNOPSIS 44.Nm 45.Sh DESCRIPTION 46The 47.Nm 48file specifies remote mount points for the 49.Tn NFS 50mount protocol per the 51.Tn NFS 52server specification; see 53.%T "Network File System Protocol Specification" , 54RFC1094, Appendix A and 55.%T "NFS: Network File System Version 3 Specification" , 56Appendix I. 57.Pp 58Each line in the file 59(other than comment lines that begin with a #) 60specifies the mount point(s) and export flags within one local server 61file system for one or more hosts. 62A long line may be split over several lines by ending all but the 63last line with a backslash 64.Pq Ql \e . 65A host may be specified only once for each local file system on the 66server and there may be only one default entry for each server 67file system that applies to all other hosts. 68The latter exports the file system to the ``world'' and should 69be used only when the file system contains public information. 70.Pp 71In a mount entry, 72the first field(s) specify the directory path(s) within a server file system 73that can be mounted on by the corresponding client(s). 74There are two forms of this specification. 75The first is to list all mount points as absolute 76directory paths separated by whitespace. 77The second is to specify the pathname of the root of the file system 78followed by the 79.Fl alldirs 80flag; 81this form allows the host(s) to mount at any point within the file system, 82including regular files if the 83.Fl r 84option is used on 85.Xr mountd 8 . 86The pathnames must not have any symbolic links in them and should not have 87any "." or ".." components. 88Mount points for a file system may appear on multiple lines each with 89different sets of hosts and export options. 90.Pp 91The second component of a line specifies how the file system is to be 92exported to the host set. 93The option flags specify whether the file system 94is exported read-only or read-write and how the client uid is mapped to 95user credentials on the server. 96.Pp 97Export options are specified as follows: 98.Pp 99.Sm off 100.Fl maproot No = Sy user 101.Sm on 102The credential of the specified user is used for remote access by root. 103The credential includes all the groups to which the user is a member 104on the local machine (see 105.Xr id 1 ) . 106The user may be specified by name or number. 107.Pp 108.Sm off 109.Fl maproot No = Sy user:group1:group2:... 110.Sm on 111The colon separated list is used to specify the precise credential 112to be used for remote access by root. 113The elements of the list may be either names or numbers. 114Note that user: should be used to distinguish a credential containing 115no groups from a complete credential for that user. 116.Pp 117.Sm off 118.Fl mapall No = Sy user 119.Sm on 120or 121.Sm off 122.Fl mapall No = Sy user:group1:group2:... 123.Sm on 124specifies a mapping for all client uids (including root) 125using the same semantics as 126.Fl maproot . 127.Pp 128The option 129.Fl r 130is a synonym for 131.Fl maproot 132in an effort to be backward compatible with older export file formats. 133.Pp 134In the absence of 135.Fl maproot 136and 137.Fl mapall 138options, remote accesses by root will result in using a credential of -2:-2. 139All other users will be mapped to their remote credential. 140If a 141.Fl maproot 142option is given, 143remote access by root will be mapped to that credential instead of -2:-2. 144If a 145.Fl mapall 146option is given, 147all users (including root) will be mapped to that credential in 148place of their own. 149.Pp 150The 151.Fl ro 152option specifies that the file system should be exported read-only 153(default read/write). 154The option 155.Fl o 156is a synonym for 157.Fl ro 158in an effort to be backward compatible with older export file formats. 159.Pp 160.Tn WebNFS 161exports strictly according to the spec (RFC 2054 and RFC 2055) can 162be done with the 163.Fl public 164flag. 165However, this flag in itself allows r/w access to all files in 166the file system, not requiring reserved ports and not remapping uids. 167It 168is only provided to conform to the spec, and should normally not be used. 169For a 170.Tn WebNFS 171export, 172use the 173.Fl webnfs 174flag, which implies 175.Fl public , 176.Sm off 177.Fl mapall No = Sy nobody 178.Sm on 179and 180.Fl ro . 181Note that only one file system can be 182.Tn WebNFS 183exported on a server. 184.Pp 185A 186.Sm off 187.Fl index No = Sy file 188.Sm on 189option can be used to specify a file whose handle will be returned if 190a directory is looked up using the public filehandle 191.Pq Tn WebNFS . 192This is to mimic the behavior of URLs. 193If no 194.Fl index 195option is specified, a directory filehandle will be returned as usual. 196The 197.Fl index 198option only makes sense in combination with the 199.Fl public 200or 201.Fl webnfs 202flags. 203.Pp 204Specifying the 205.Fl quiet 206option will inhibit some of the syslog diagnostics for bad lines in 207.Pa /etc/exports . 208This can be useful to avoid annoying error messages for known possible 209problems (see 210.Sx EXAMPLES 211below). 212.Pp 213The third component of a line specifies the host set to which the line applies. 214The set may be specified in three ways. 215The first way is to list the host name(s) separated by white space. 216(Standard Internet ``dot'' addresses may be used in place of names.) 217The second way is to specify a ``netgroup'' as defined in the netgroup file (see 218.Xr netgroup 5 ) . 219The third way is to specify an Internet subnetwork using a network and 220network mask that is defined as the set of all hosts with addresses within 221the subnetwork. 222This latter approach requires less overhead within the 223kernel and is recommended for cases where the export line refers to a 224large number of clients within an administrative subnet. 225.Pp 226The first two cases are specified by simply listing the name(s) separated 227by whitespace. 228All names are checked to see if they are ``netgroup'' names 229first and are assumed to be hostnames otherwise. 230Using the full domain specification for a hostname can normally 231circumvent the problem of a host that has the same name as a netgroup. 232The third case is specified by the flag 233.Sm off 234.Fl network No = Sy netname 235.Sm on 236and optionally 237.Sm off 238.Fl mask No = Sy netmask . 239.Sm on 240If the mask is not specified, it will default to the mask for that network 241class (A, B or C; see 242.Xr inet 4 ) . 243See the 244.Sx EXAMPLES 245section below. 246.Pp 247The 248.Xr mountd 8 249utility can be made to re-read the 250.Nm 251file by sending it a hangup signal as follows: 252.Bd -literal -offset indent 253kill -s HUP `cat /var/run/mountd.pid` 254.Ed 255.Pp 256After sending the 257.Dv SIGHUP , 258check the 259.Xr syslogd 8 260output to see whether 261.Xr mountd 8 262logged any parsing errors in the 263.Nm 264file. 265.Sh FILES 266.Bl -tag -width /etc/exports -compact 267.It Pa /etc/exports 268the default remote mount-point file 269.El 270.Sh EXAMPLES 271.Bd -literal -offset indent 272/usr /usr/local -maproot=0:10 friends 273/usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16 274/usr -ro -mapall=nobody 275/u -maproot=bin: -network 131.104.48 -mask 255.255.255.0 276/u2 -maproot=root friends 277/u2 -alldirs -network cis-net -mask cis-mask 278/cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask 255.255.255.0 279.Ed 280.Pp 281Given that 282.Sy /usr , 283.Sy /u 284and 285.Sy /u2 286are 287local file system mount points, the above example specifies the following: 288.Pp 289.Sy /usr 290is exported to hosts 291.Em friends 292where friends is specified in the netgroup file 293with users mapped to their remote credentials and 294root mapped to uid 0 and group 10. 295It is exported read-write and the hosts in ``friends'' can mount either /usr 296or /usr/local. 297It is exported to 298.Em 131.104.48.16 299and 300.Em grumpy.cis.uoguelph.ca 301with users mapped to their remote credentials and 302root mapped to the user and groups associated with ``daemon''; 303it is exported to the rest of the world as read-only with 304all users mapped to the user and groups associated with ``nobody''. 305.Pp 306.Sy /u 307is exported to all hosts on the subnetwork 308.Em 131.104.48 309with root mapped to the uid for ``bin'' and with no group access. 310.Pp 311.Sy /u2 312is exported to the hosts in ``friends'' with root mapped to uid and groups 313associated with ``root''; 314it is exported to all hosts on network ``cis-net'' allowing mounts at any 315directory within /u2. 316.Pp 317The file system rooted at 318.Sy /cdrom 319will exported read-only to the entire network 192.168.33.0/24, including 320all its subdirectories. 321Since 322.Sy /cdrom 323is the conventional mountpoint for a CD-ROM device, this export will 324fail if no CD-ROM medium is currently mounted there since that line 325would then attempt to export a subdirectory of the root file system 326with the 327.Fl alldirs 328option which is not allowed. 329The 330.Fl quiet 331option will then suppress the error message for this condition that 332would normally be syslogged. 333As soon as an actual CD-ROM is going to be mounted, 334.Xr mount 8 335will notify 336.Xr mountd 8 337about this situation, and the 338.Sy /cdrom 339file system will be exported as intended. 340Note that without using the 341.Fl alldirs 342option, the export would always succeed. 343While there is no CD-ROM medium mounted under 344.Sy /cdrom , 345it would export the (normally empty) directory 346.Sy /cdrom 347of the root file system instead. 348.Sh SEE ALSO 349.Xr netgroup 5 , 350.Xr mountd 8 , 351.Xr nfsd 8 , 352.Xr showmount 8 353.Sh BUGS 354The export options are tied to the local mount points in the kernel and 355must be non-contradictory for any exported subdirectory of the local 356server mount point. 357It is recommended that all exported directories within the same server 358file system be specified on adjacent lines going down the tree. 359You cannot specify a hostname that is also the name of a netgroup. 360Specifying the full domain specification for a hostname can normally 361circumvent the problem. 362