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.\" 4. 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.\" $FreeBSD$ 30.\" 31.Dd March 29, 1995 32.Dt EXPORTS 5 33.Os 34.Sh NAME 35.Nm exports 36.Nd define remote mount points for 37.Tn NFS 38mount requests 39.Sh SYNOPSIS 40.Nm 41.Sh DESCRIPTION 42The 43.Nm 44file specifies remote mount points for the 45.Tn NFS 46mount protocol per the 47.Tn NFS 48server specification; see 49.%T "Network File System Protocol Specification" , 50RFC1094, Appendix A and 51.%T "NFS: Network File System Version 3 Specification" , 52Appendix I. 53.Pp 54Each line in the file 55(other than comment lines that begin with a #) 56specifies the mount point(s) and export flags within one local server 57file system for one or more hosts. 58A long line may be split over several lines by ending all but the 59last line with a backslash 60.Pq Ql \e . 61A host may be specified only once for each local file system on the 62server and there may be only one default entry for each server 63file system that applies to all other hosts. 64The latter exports the file system to the ``world'' and should 65be used only when the file system contains public information. 66.Pp 67In a mount entry, 68the first field(s) specify the directory path(s) within a server file system 69that can be mounted on by the corresponding client(s). 70There are two forms of this specification. 71The first is to list all mount points as absolute 72directory paths separated by whitespace. 73The second is to specify the pathname of the root of the file system 74followed by the 75.Fl alldirs 76flag; 77this form allows the host(s) to mount at any point within the file system, 78including regular files if the 79.Fl r 80option is used on 81.Xr mountd 8 . 82The pathnames must not have any symbolic links in them and should not have 83any "." or ".." components. 84Mount points for a file system may appear on multiple lines each with 85different sets of hosts and export options. 86.Pp 87The second component of a line specifies how the file system is to be 88exported to the host set. 89The option flags specify whether the file system 90is exported read-only or read-write and how the client uid is mapped to 91user credentials on the server. 92.Pp 93Export options are specified as follows: 94.Pp 95.Sm off 96.Fl maproot No = Sy user 97.Sm on 98The credential of the specified user is used for remote access by root. 99The credential includes all the groups to which the user is a member 100on the local machine (see 101.Xr id 1 ) . 102The user may be specified by name or number. 103.Pp 104.Sm off 105.Fl maproot No = Sy user:group1:group2:... 106.Sm on 107The colon separated list is used to specify the precise credential 108to be used for remote access by root. 109The elements of the list may be either names or numbers. 110Note that user: should be used to distinguish a credential containing 111no groups from a complete credential for that user. 112.Pp 113.Sm off 114.Fl mapall No = Sy user 115.Sm on 116or 117.Sm off 118.Fl mapall No = Sy user:group1:group2:... 119.Sm on 120specifies a mapping for all client uids (including root) 121using the same semantics as 122.Fl maproot . 123.Pp 124The option 125.Fl r 126is a synonym for 127.Fl maproot 128in an effort to be backward compatible with older export file formats. 129.Pp 130In the absence of 131.Fl maproot 132and 133.Fl mapall 134options, remote accesses by root will result in using a credential of -2:-2. 135All other users will be mapped to their remote credential. 136If a 137.Fl maproot 138option is given, 139remote access by root will be mapped to that credential instead of -2:-2. 140If a 141.Fl mapall 142option is given, 143all users (including root) will be mapped to that credential in 144place of their own. 145.Pp 146The 147.Fl ro 148option specifies that the file system should be exported read-only 149(default read/write). 150The option 151.Fl o 152is a synonym for 153.Fl ro 154in an effort to be backward compatible with older export file formats. 155.Pp 156.Tn WebNFS 157exports strictly according to the spec (RFC 2054 and RFC 2055) can 158be done with the 159.Fl public 160flag. 161However, this flag in itself allows r/w access to all files in 162the file system, not requiring reserved ports and not remapping uids. 163It 164is only provided to conform to the spec, and should normally not be used. 165For a 166.Tn WebNFS 167export, 168use the 169.Fl webnfs 170flag, which implies 171.Fl public , 172.Sm off 173.Fl mapall No = Sy nobody 174.Sm on 175and 176.Fl ro . 177Note that only one file system can be 178.Tn WebNFS 179exported on a server. 180.Pp 181A 182.Sm off 183.Fl index No = Pa file 184.Sm on 185option can be used to specify a file whose handle will be returned if 186a directory is looked up using the public filehandle 187.Pq Tn WebNFS . 188This is to mimic the behavior of URLs. 189If no 190.Fl index 191option is specified, a directory filehandle will be returned as usual. 192The 193.Fl index 194option only makes sense in combination with the 195.Fl public 196or 197.Fl webnfs 198flags. 199.Pp 200Specifying the 201.Fl quiet 202option will inhibit some of the syslog diagnostics for bad lines in 203.Pa /etc/exports . 204This can be useful to avoid annoying error messages for known possible 205problems (see 206.Sx EXAMPLES 207below). 208.Pp 209The third component of a line specifies the host set to which the line applies. 210The set may be specified in three ways. 211The first way is to list the host name(s) separated by white space. 212(Standard Internet ``dot'' addresses may be used in place of names.) 213The second way is to specify a ``netgroup'' as defined in the netgroup file (see 214.Xr netgroup 5 ) . 215The third way is to specify an Internet subnetwork using a network and 216network mask that is defined as the set of all hosts with addresses within 217the subnetwork. 218This latter approach requires less overhead within the 219kernel and is recommended for cases where the export line refers to a 220large number of clients within an administrative subnet. 221.Pp 222The first two cases are specified by simply listing the name(s) separated 223by whitespace. 224All names are checked to see if they are ``netgroup'' names 225first and are assumed to be hostnames otherwise. 226Using the full domain specification for a hostname can normally 227circumvent the problem of a host that has the same name as a netgroup. 228The third case is specified by the flag 229.Sm off 230.Fl network No = Sy netname 231.Sm on 232and optionally 233.Sm off 234.Fl mask No = Sy netmask . 235.Sm on 236If the mask is not specified, it will default to the mask for that network 237class (A, B or C; see 238.Xr inet 4 ) . 239See the 240.Sx EXAMPLES 241section below. 242.Pp 243The 244.Xr mountd 8 245utility can be made to re-read the 246.Nm 247file by sending it a hangup signal as follows: 248.Bd -literal -offset indent 249kill -s HUP `cat /var/run/mountd.pid` 250.Ed 251.Pp 252After sending the 253.Dv SIGHUP , 254check the 255.Xr syslogd 8 256output to see whether 257.Xr mountd 8 258logged any parsing errors in the 259.Nm 260file. 261.Sh FILES 262.Bl -tag -width /etc/exports -compact 263.It Pa /etc/exports 264the default remote mount-point file 265.El 266.Sh EXAMPLES 267.Bd -literal -offset indent 268/usr /usr/local -maproot=0:10 friends 269/usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16 270/usr -ro -mapall=nobody 271/u -maproot=bin: -network 131.104.48 -mask 255.255.255.0 272/u2 -maproot=root friends 273/u2 -alldirs -network cis-net -mask cis-mask 274/cdrom -alldirs,quiet,ro -network 192.168.33.0 -mask 255.255.255.0 275.Ed 276.Pp 277Given that 278.Pa /usr , 279.Pa /u 280and 281.Pa /u2 282are 283local file system mount points, the above example specifies the following: 284.Pp 285.Pa /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.Pa /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.Pa /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.Pa /cdrom 315will exported read-only to the entire network 192.168.33.0/24, including 316all its subdirectories. 317Since 318.Pa /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.Pa /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.Pa /cdrom , 341it would export the (normally empty) directory 342.Pa /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