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.\" $Id$ 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 exports 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 mountd. 81The pathnames must not have any symbolic links in them and should not have 82any "." or ".." components. 83Mount points for a filesystem may appear on multiple lines each with 84different sets of hosts and export options. 85.Pp 86The second component of a line specifies how the filesystem is to be 87exported to the host set. 88The option flags specify whether the filesystem 89is exported read-only or read-write and how the client uid is mapped to 90user credentials on the server. 91.Pp 92Export options are specified as follows: 93.Pp 94.Sm off 95.Fl maproot No = Sy user 96.Sm on 97The credential of the specified user is used for remote access by root. 98The credential includes all the groups to which the user is a member 99on the local machine (see 100.Xr id 1 ). 101The user may be specified by name or number. 102.Pp 103.Sm off 104.Fl maproot No = Sy user:group1:group2:... 105.Sm on 106The colon separated list is used to specify the precise credential 107to be used for remote access by root. 108The elements of the list may be either names or numbers. 109Note that user: should be used to distinguish a credential containing 110no groups from a complete credential for that user. 111.Pp 112.Sm off 113.Fl mapall No = Sy user 114.Sm on 115or 116.Sm off 117.Fl mapall No = Sy user:group1:group2:... 118.Sm on 119specifies a mapping for all client uids (including root) 120using the same semantics as 121.Fl maproot . 122.Pp 123The option 124.Fl r 125is a synonym for 126.Fl maproot 127in an effort to be backward compatible with older export file formats. 128.Pp 129In the absence of 130.Fl maproot 131and 132.Fl mapall 133options, remote accesses by root will result in using a credential of -2:-2. 134All other users will be mapped to their remote credential. 135If a 136.Fl maproot 137option is given, 138remote access by root will be mapped to that credential instead of -2:-2. 139If a 140.Fl mapall 141option is given, 142all users (including root) will be mapped to that credential in 143place of their own. 144.Pp 145The 146.Fl kerb 147option specifies that the Kerberos authentication server should be 148used to authenticate and map client credentials. 149This option requires that the kernel be built with the NFSKERB option. 150.Pp 151The 152.Fl ro 153option specifies that the filesystem should be exported read-only 154(default read/write). 155The option 156.Fl o 157is a synonym for 158.Fl ro 159in an effort to be backward compatible with older export file formats. 160.Pp 161The third component of a line specifies the host set to which the line applies. 162The set may be specified in three ways. 163The first way is to list the host name(s) separated by white space. 164(Standard internet ``dot'' addresses may be used in place of names.) 165The second way is to specify a ``netgroup'' as defined in the netgroup file (see 166.Xr netgroup 5 ). 167The third way is to specify an internet subnetwork using a network and 168network mask that is defined as the set of all hosts with addresses within 169the subnetwork. 170This latter approach requires less overhead within the 171kernel and is recommended for cases where the export line refers to a 172large number of clients within an administrative subnet. 173.Pp 174The first two cases are specified by simply listing the name(s) separated 175by whitespace. 176All names are checked to see if they are ``netgroup'' names 177first and are assumed to be hostnames otherwise. 178Using the full domain specification for a hostname can normally 179circumvent the problem of a host that has the same name as a netgroup. 180The third case is specified by the flag 181.Sm off 182.Fl network No = Sy netname 183.Sm on 184and optionally 185.Sm off 186.Fl mask No = Sy netmask . 187.Sm on 188If the mask is not specified, it will default to the mask for that network 189class (A, B or C; see 190.Xr inet 4 ). 191.Pp 192For example: 193.Bd -literal -offset indent 194/usr /usr/local -maproot=0:10 friends 195/usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16 196/usr -ro -mapall=nobody 197/u -maproot=bin: -network 131.104.48 -mask 255.255.255.0 198/u2 -maproot=root friends 199/u2 -alldirs -kerb -network cis-net -mask cis-mask 200.Ed 201.Pp 202Given that 203.Sy /usr , 204.Sy /u 205and 206.Sy /u2 207are 208local filesystem mount points, the above example specifies the following: 209.Sy /usr 210is exported to hosts 211.Em friends 212where friends is specified in the netgroup file 213with users mapped to their remote credentials and 214root mapped to uid 0 and group 10. 215It is exported read-write and the hosts in ``friends'' can mount either /usr 216or /usr/local. 217It is exported to 218.Em 131.104.48.16 219and 220.Em grumpy.cis.uoguelph.ca 221with users mapped to their remote credentials and 222root mapped to the user and groups associated with ``daemon''; 223it is exported to the rest of the world as read-only with 224all users mapped to the user and groups associated with ``nobody''. 225.Pp 226.Sy /u 227is exported to all hosts on the subnetwork 228.Em 131.104.48 229with root mapped to the uid for ``bin'' and with no group access. 230.Pp 231.Sy /u2 232is exported to the hosts in ``friends'' with root mapped to uid and groups 233associated with ``root''; 234it is exported to all hosts on network ``cis-net'' allowing mounts at any 235directory within /u2 and mapping all uids to credentials for the principal 236that is authenticated by a Kerberos ticket. 237.Sh FILES 238.Bl -tag -width /etc/exports -compact 239.It Pa /etc/exports 240The default remote mount-point file. 241.El 242.Sh SEE ALSO 243.Xr netgroup 5 , 244.Xr mountd 8 , 245.Xr nfsd 8 , 246.Xr showmount 8 247.Sh BUGS 248The export options are tied to the local mount points in the kernel and 249must be non-contradictory for any exported subdirectory of the local 250server mount point. 251It is recommended that all exported directories within the same server 252filesystem be specified on adjacent lines going down the tree. 253You cannot specify a hostname that is also the name of a netgroup. 254Specifying the full domain specification for a hostname can normally 255circumvent the problem. 256