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 61filesystem 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 filesystem on the 66server and there may be only one default entry for each server 67filesystem that applies to all other hosts. 68The latter exports the filesystem to the ``world'' and should 69be used only when the filesystem contains public information. 70.Pp 71In a mount entry, 72the first field(s) specify the directory path(s) within a server filesystem 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 filesystem 78followed by the 79.Fl alldirs 80flag; 81this form allows the host(s) to mount at any point within the filesystem, 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 filesystem 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 filesystem is to be 92exported to the host set. 93The option flags specify whether the filesystem 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 kerb 152option specifies that the Kerberos authentication server should be 153used to authenticate and map client credentials. 154This option requires that the kernel be built with the NFSKERB option. 155The use of this option will prevent the kernel from compiling 156unless calls to the appropriate Kerberos encryption routines 157are provided in the NFS source. 158.Pp 159The 160.Fl ro 161option specifies that the filesystem should be exported read-only 162(default read/write). 163The option 164.Fl o 165is a synonym for 166.Fl ro 167in an effort to be backward compatible with older export file formats. 168.Pp 169.Tn WebNFS 170exports strictly according to the spec (RFC 2054 and RFC 2055) can 171be done with the 172.Fl public 173flag. 174However, this flag in itself allows r/w access to all files in 175the filesystem, not requiring reserved ports and not remapping uids. 176It 177is only provided to conform to the spec, and should normally not be used. 178For a 179.Tn WebNFS 180export, 181use the 182.Fl webnfs 183flag, which implies 184.Fl public , 185.Sm off 186.Fl mapall No = Sy nobody 187.Sm on 188and 189.Fl ro . 190.Pp 191A 192.Sm off 193.Fl index No = Sy file 194.Sm on 195option can be used to specify a file whose handle will be returned if 196a directory is looked up using the public filehandle 197.Pq Tn WebNFS . 198This is to mimic the behavior of URLs. 199If no 200.Fl index 201option is specified, a directory filehandle will be returned as usual. 202The 203.Fl index 204option only makes sense in combination with the 205.Fl public 206or 207.Fl webnfs 208flags. 209.Pp 210Specifying the 211.Fl quiet 212option will inhibit some of the syslog diagnostics for bad lines in 213.Pa /etc/exports . 214This can be useful to avoid annoying error messages for known possible 215problems (see 216.Sx EXAMPLES 217below). 218.Pp 219The third component of a line specifies the host set to which the line applies. 220The set may be specified in three ways. 221The first way is to list the host name(s) separated by white space. 222(Standard Internet ``dot'' addresses may be used in place of names.) 223The second way is to specify a ``netgroup'' as defined in the netgroup file (see 224.Xr netgroup 5 ) . 225The third way is to specify an Internet subnetwork using a network and 226network mask that is defined as the set of all hosts with addresses within 227the subnetwork. 228This latter approach requires less overhead within the 229kernel and is recommended for cases where the export line refers to a 230large number of clients within an administrative subnet. 231.Pp 232The first two cases are specified by simply listing the name(s) separated 233by whitespace. 234All names are checked to see if they are ``netgroup'' names 235first and are assumed to be hostnames otherwise. 236Using the full domain specification for a hostname can normally 237circumvent the problem of a host that has the same name as a netgroup. 238The third case is specified by the flag 239.Sm off 240.Fl network No = Sy netname 241.Sm on 242and optionally 243.Sm off 244.Fl mask No = Sy netmask . 245.Sm on 246If the mask is not specified, it will default to the mask for that network 247class (A, B or C; see 248.Xr inet 4 ) . 249See the 250.Sx EXAMPLES 251section below. 252.Pp 253The 254.Xr mountd 8 255utility can be made to re-read the 256.Nm 257file by sending it a hangup signal as follows: 258.Bd -literal -offset indent 259kill -s HUP `cat /var/run/mountd.pid` 260.Ed 261.Pp 262After sending the 263.Dv SIGHUP , 264check the 265.Xr syslogd 8 266output to see whether 267.Xr mountd 8 268logged any parsing errors in the 269.Nm 270file. 271.Sh FILES 272.Bl -tag -width /etc/exports -compact 273.It Pa /etc/exports 274the default remote mount-point file 275.El 276.Sh EXAMPLES 277.Bd -literal -offset indent 278/usr /usr/local -maproot=0:10 friends 279/usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16 280/usr -ro -mapall=nobody 281/u -maproot=bin: -network 131.104.48 -mask 255.255.255.0 282/u2 -maproot=root friends 283/u2 -alldirs -kerb -network cis-net -mask cis-mask 284/cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask 255.255.255.0 285.Ed 286.Pp 287Given that 288.Sy /usr , 289.Sy /u 290and 291.Sy /u2 292are 293local filesystem mount points, the above example specifies the following: 294.Sy /usr 295is exported to hosts 296.Em friends 297where friends is specified in the netgroup file 298with users mapped to their remote credentials and 299root mapped to uid 0 and group 10. 300It is exported read-write and the hosts in ``friends'' can mount either /usr 301or /usr/local. 302It is exported to 303.Em 131.104.48.16 304and 305.Em grumpy.cis.uoguelph.ca 306with users mapped to their remote credentials and 307root mapped to the user and groups associated with ``daemon''; 308it is exported to the rest of the world as read-only with 309all users mapped to the user and groups associated with ``nobody''. 310.Pp 311.Sy /u 312is exported to all hosts on the subnetwork 313.Em 131.104.48 314with root mapped to the uid for ``bin'' and with no group access. 315.Pp 316.Sy /u2 317is exported to the hosts in ``friends'' with root mapped to uid and groups 318associated with ``root''; 319it is exported to all hosts on network ``cis-net'' allowing mounts at any 320directory within /u2 and mapping all uids to credentials for the principal 321that is authenticated by a Kerberos ticket. 322.Pp 323The filesystem rooted at 324.Sy /cdrom 325will exported read-only to the entire network 192.168.33.0/24, including 326all its subdirectories. 327Since 328.Sy /cdrom 329is the conventional mountpoint for a CD-ROM device, this export will 330fail if no CD-ROM medium is currently mounted there since that line 331would then attempt to export a subdirectory of the root filesystem 332with the 333.Fl alldirs 334option which is not allowed. 335The 336.Fl quiet 337option will then suppress the error message for this condition that 338would normally be syslogged. 339As soon as an actual CD-ROM is going to be mounted, 340.Xr mount 8 341will notify 342.Xr mountd 8 343about this situation, and the 344.Sy /cdrom 345filesystem will be exported as intented. 346Note that without using the 347.Fl alldirs 348option, the export would always succeed. 349While there is no CD-ROM medium mounted under 350.Sy /cdrom , 351it would export the (normally empty) directory 352.Sy /cdrom 353of the root filesystem instead. 354.Sh SEE ALSO 355.Xr netgroup 5 , 356.Xr mountd 8 , 357.Xr nfsd 8 , 358.Xr showmount 8 359.Sh BUGS 360The export options are tied to the local mount points in the kernel and 361must be non-contradictory for any exported subdirectory of the local 362server mount point. 363It is recommended that all exported directories within the same server 364filesystem be specified on adjacent lines going down the tree. 365You cannot specify a hostname that is also the name of a netgroup. 366Specifying the full domain specification for a hostname can normally 367circumvent the problem. 368