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 8.2 (Berkeley) 1/28/94 33.\" 34.Dd January 28, 1994 35.Dt EXPORTS 5 36.Os 37.Sh NAME 38.Nm exports 39.Nd define remote mount points for 40.Tn NFS 41mount requests 42.Sh SYNOPSIS 43.Nm exports 44.Sh DESCRIPTION 45The 46.Nm exports 47file specifies remote mount points for the 48.Tn NFS 49mount protocol per the 50.Tn NFS 51server specification; see 52.%T "Network File System Protocol Specification \\*(tNRFC\\*(sP 1094, Appendix A" 53and 54.%T "NFS: Network File System Version 3 Specification, Appendix I" . 55.Pp 56Each line in the file 57(other than comment lines that begin with a #) 58specifies the mount point(s) and export flags within one local server 59filesystem for one or more hosts. 60A host may be specified only once for each local filesystem on the 61server and there may be only one default entry for each server 62filesystem that applies to all other hosts. 63The latter exports the filesystem to the ``world'' and should 64be used only when the filesystem contains public information. 65.Pp 66In a mount entry, 67the first field(s) specify the directory path(s) within a server filesystem 68that can be mounted on by the corresponding client(s). 69There are two forms of this specification. 70The first is to list all mount points as absolute 71directory paths separated by whitespace. 72The second is to specify the pathname of the root of the filesystem 73followed by the 74.Fl alldirs 75flag; 76this form allows the host(s) to mount at any point within the filesystem, 77including regular files if the ``-r'' option is used on mountd. 78The pathnames must not have any symbolic links in them and should not have 79any "." or ".." components. 80Mount points for a filesystem may appear on multiple lines each with 81different sets of hosts and export options. 82.Pp 83The second component of a line specifies how the filesystem is to be 84exported to the host set. 85The option flags specify whether the filesystem 86is exported read-only or read-write and how the client uid is mapped to 87user credentials on the server. 88.Pp 89Export options are specified as follows: 90.Pp 91.Sm off 92.Fl maproot No = Sy user 93.Sm on 94The credential of the specified user is used for remote access by root. 95The credential includes all the groups to which the user is a member 96on the local machine (see 97.Xr id 1 ). 98The user may be specified by name or number. 99.Pp 100.Sm off 101.Fl maproot No = Sy user:group1:group2:... 102.Sm on 103The colon separated list is used to specify the precise credential 104to be used for remote access by root. 105The elements of the list may be either names or numbers. 106Note that user: should be used to distinguish a credential containing 107no groups from a complete credential for that user. 108.Pp 109.Sm off 110.Fl mapall No = Sy user 111.Sm on 112or 113.Sm off 114.Fl mapall No = Sy user:group1:group2:... 115.Sm on 116specifies a mapping for all client uids (including root) 117using the same semantics as 118.Fl maproot . 119.Pp 120The option 121.Fl r 122is a synonym for 123.Fl maproot 124in an effort to be backward compatible with older export file formats. 125.Pp 126In the absence of 127.Fl maproot 128and 129.Fl mapall 130options, remote accesses by root will result in using a credential of -2:-2. 131All other users will be mapped to their remote credential. 132If a 133.Fl maproot 134option is given, 135remote access by root will be mapped to that credential instead of -2:-2. 136If a 137.Fl mapall 138option is given, 139all users (including root) will be mapped to that credential in 140place of their own. 141.Pp 142The 143.Fl kerb 144option specifies that the Kerberos authentication server should be 145used to authenticate and map client credentials. 146This requires that the kernel be built with the NFSKERB option. 147.Pp 148The 149.Fl ro 150option specifies that the filesystem should be exported read-only 151(default read/write). 152The option 153.Fl o 154is a synonym for 155.Fl ro 156in an effort to be backward compatible with older export file formats. 157.Pp 158The third component of a line specifies the host set to which the line applies. 159The set may be specified in three ways. 160The first way is to list the host name(s) separated by white space. 161(Standard internet ``dot'' addresses may be used in place of names.) 162The second way is to specify a ``netgroup'' as defined in the netgroup file (see 163.Xr netgroup 5 ). 164The third way is to specify an internet subnetwork using a network and 165network mask that is defined as the set of all hosts with addresses within 166the subnetwork. 167This latter approach requires less overhead within the 168kernel and is recommended for cases where the export line refers to a 169large number of clients within an administrative subnet. 170.Pp 171The first two cases are specified by simply listing the name(s) separated 172by whitespace. 173All names are checked to see if they are ``netgroup'' names 174first and are assumed to be hostnames otherwise. 175Using the full domain specification for a hostname can normally 176circumvent the problem of a host that has the same name as a netgroup. 177The third case is specified by the flag 178.Sm off 179.Fl network No = Sy netname 180.Sm on 181and optionally 182.Sm off 183.Fl mask No = Sy netmask . 184.Sm on 185If the mask is not specified, it will default to the mask for that network 186class (A, B or C; see 187.Xr inet 5 ). 188.Pp 189For example: 190.Bd -literal -offset indent 191/usr /usr/local -maproot=0:10 friends 192/usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16 193/usr -ro -mapall=nobody 194/u -maproot=bin: -network 131.104.48 -mask 255.255.255.0 195/u2 -maproot=root friends 196/u2 -alldirs -kerb -network cis-net -mask cis-mask 197.Ed 198.Pp 199Given that 200.Sy /usr , 201.Sy /u 202and 203.Sy /u2 204are 205local filesystem mount points, the above example specifies the following: 206.Sy /usr 207is exported to hosts 208.Em friends 209where friends is specified in the netgroup file 210with users mapped to their remote credentials and 211root mapped to uid 0 and group 10. 212It is exported read-write and the hosts in ``friends'' can mount either /usr 213or /usr/local. 214It is exported to 215.Em 131.104.48.16 216and 217.Em grumpy.cis.uoguelph.ca 218with users mapped to their remote credentials and 219root mapped to the user and groups associated with ``daemon''; 220it is exported to the rest of the world as read-only with 221all users mapped to the user and groups associated with ``nobody''. 222.Pp 223.Sy /u 224is exported to all hosts on the subnetwork 225.Em 131.104.48 226with root mapped to the uid for ``bin'' and with no group access. 227.Pp 228.Sy /u2 229is exported to the hosts in ``friends'' with root mapped to uid and groups 230associated with ``root''; 231it is exported to all hosts on network ``cis-net'' allowing mounts at any 232directory within /u2 and mapping all uids to credentials for the principal 233that is authenticated by a Kerberos ticket. 234.Sh FILES 235.Bl -tag -width /etc/exports -compact 236.It Pa /etc/exports 237The default remote mount-point file. 238.El 239.Sh SEE ALSO 240.Xr netgroup 5 , 241.Xr mountd 8 , 242.Xr nfsd 8 , 243.Xr showmount 8 244.Sh BUGS 245The export options are tied to the local mount points in the kernel and 246must be non-contradictory for any exported subdirectory of the local 247server mount point. 248It is recommended that all exported directories within the same server 249filesystem be specified on adjacent lines going down the tree. 250You cannot specify a hostname that is also the name of a netgroup. 251Specifying the full domain specification for a hostname can normally 252circumvent the problem. 253