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