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 exports 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 \\*(tNRFC\\*(sP 1094, Appendix A" 54and 55.%T "NFS: Network File System Version 3 Specification, Appendix I" . 56.Pp 57Each line in the file 58(other than comment lines that begin with a #) 59specifies the mount point(s) and export flags within one local server 60filesystem for one or more hosts. 61A host may be specified only once for each local filesystem on the 62server and there may be only one default entry for each server 63filesystem that applies to all other hosts. 64The latter exports the filesystem to the ``world'' and should 65be used only when the filesystem contains public information. 66.Pp 67In a mount entry, 68the first field(s) specify the directory path(s) within a server filesystem 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 filesystem 74followed by the 75.Fl alldirs 76flag; 77this form allows the host(s) to mount at any point within the filesystem, 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 filesystem 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 filesystem is to be 88exported to the host set. 89The option flags specify whether the filesystem 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 kerb 148option specifies that the Kerberos authentication server should be 149used to authenticate and map client credentials. 150This option requires that the kernel be built with the NFSKERB option. 151.Pp 152The 153.Fl ro 154option specifies that the filesystem should be exported read-only 155(default read/write). 156The option 157.Fl o 158is a synonym for 159.Fl ro 160in an effort to be backward compatible with older export file formats. 161.Pp 162.Tn WebNFS 163exports strictly according to the spec (RFC 2054 and RFC 2055) can 164be done with the 165.Fl public 166flag. 167However, this flag in itself allows r/w access to all files in 168the filesystem, not requiring reserved ports and not remapping uids. 169It 170is only provided to conform to the spec, and should normally not be used. 171For a 172.Tn WebNFS 173export, 174use the 175.Fl webnfs 176flag, which implies 177.Fl public , 178.Sm off 179.Fl mapall No = Sy nobody 180.Sm on 181and 182.Fl ro . 183.Pp 184A 185.Sm off 186.Fl index No = Sy file 187.Sm on 188option can be used to specify a file whose handle will be returned if 189a directory is looked up using the public filehandle ( 190.Tn WebNFS Ns ). 191This is to mimic the behavior of URLs. 192If no 193.Fl index 194option is specified, a directory filehandle will be returned as usual. 195The 196.Fl index 197option only makes sense in combination with the 198.Fl public 199or 200.Fl webnfs 201flags. 202.Pp 203The third component of a line specifies the host set to which the line applies. 204The set may be specified in three ways. 205The first way is to list the host name(s) separated by white space. 206(Standard Internet ``dot'' addresses may be used in place of names.) 207The second way is to specify a ``netgroup'' as defined in the netgroup file (see 208.Xr netgroup 5 ). 209The third way is to specify an Internet subnetwork using a network and 210network mask that is defined as the set of all hosts with addresses within 211the subnetwork. 212This latter approach requires less overhead within the 213kernel and is recommended for cases where the export line refers to a 214large number of clients within an administrative subnet. 215.Pp 216The first two cases are specified by simply listing the name(s) separated 217by whitespace. 218All names are checked to see if they are ``netgroup'' names 219first and are assumed to be hostnames otherwise. 220Using the full domain specification for a hostname can normally 221circumvent the problem of a host that has the same name as a netgroup. 222The third case is specified by the flag 223.Sm off 224.Fl network No = Sy netname 225.Sm on 226and optionally 227.Sm off 228.Fl mask No = Sy netmask . 229.Sm on 230If the mask is not specified, it will default to the mask for that network 231class (A, B or C; see 232.Xr inet 4 ). 233.Pp 234For example: 235.Bd -literal -offset indent 236/usr /usr/local -maproot=0:10 friends 237/usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16 238/usr -ro -mapall=nobody 239/u -maproot=bin: -network 131.104.48 -mask 255.255.255.0 240/u2 -maproot=root friends 241/u2 -alldirs -kerb -network cis-net -mask cis-mask 242.Ed 243.Pp 244Given that 245.Sy /usr , 246.Sy /u 247and 248.Sy /u2 249are 250local filesystem mount points, the above example specifies the following: 251.Sy /usr 252is exported to hosts 253.Em friends 254where friends is specified in the netgroup file 255with users mapped to their remote credentials and 256root mapped to uid 0 and group 10. 257It is exported read-write and the hosts in ``friends'' can mount either /usr 258or /usr/local. 259It is exported to 260.Em 131.104.48.16 261and 262.Em grumpy.cis.uoguelph.ca 263with users mapped to their remote credentials and 264root mapped to the user and groups associated with ``daemon''; 265it is exported to the rest of the world as read-only with 266all users mapped to the user and groups associated with ``nobody''. 267.Pp 268.Sy /u 269is exported to all hosts on the subnetwork 270.Em 131.104.48 271with root mapped to the uid for ``bin'' and with no group access. 272.Pp 273.Sy /u2 274is exported to the hosts in ``friends'' with root mapped to uid and groups 275associated with ``root''; 276it is exported to all hosts on network ``cis-net'' allowing mounts at any 277directory within /u2 and mapping all uids to credentials for the principal 278that is authenticated by a Kerberos ticket. 279.Sh FILES 280.Bl -tag -width /etc/exports -compact 281.It Pa /etc/exports 282the default remote mount-point file 283.El 284.Sh SEE ALSO 285.Xr netgroup 5 , 286.Xr mountd 8 , 287.Xr nfsd 8 , 288.Xr showmount 8 289.Sh BUGS 290The export options are tied to the local mount points in the kernel and 291must be non-contradictory for any exported subdirectory of the local 292server mount point. 293It is recommended that all exported directories within the same server 294filesystem be specified on adjacent lines going down the tree. 295You cannot specify a hostname that is also the name of a netgroup. 296Specifying the full domain specification for a hostname can normally 297circumvent the problem. 298