.\" Copyright (c) 1989, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\" %sccs.include.redist.roff%
.\" @(#)exports.5 8.1 (Berkeley) %G%
.Nd define remote mount points for
file specifies remote mount points for the
server specification; see
.%T "Network File System Protocol Specification \\*(tNRFC\\*(sP 1094, Appendix A" .
(other than comment lines that begin with a #)
specifies the mount point(s) and export flags within one local server
filesystem for one or more hosts.
A host may be specified only once for each local filesystem on the
server and there may be only one default entry for each server
filesystem that applies to all other hosts.
The latter exports the filesystem to the ``world'' and should
be used only when the filesystem contains public information.
the first field(s) specify the directory path(s) within a server filesystem
that can be mounted on by the corresponding client(s).
There are two forms of this specification.
The first is to list all mount points as absolute
directory paths separated by whitespace.
The second is to specify the pathname of the root of the filesystem
this form allows the host(s) to mount any directory within the filesystem.
Mount points for a filesystem may appear on multiple lines each with
different sets of hosts and export options.
The second component of a line specifies how the filesystem is to be
exported to the host set.
The option flags specify whether the filesystem
is exported read-only or read-write and how the client uid is mapped to
user credentials on the server.
Export options are specified as follows:
The credential of the specified user is used for remote access by root.
The credential includes all the groups to which the user is a member
on the local machine (see
The user may be specified by name or number.
.Fl maproot No = Sy user:group1:group2:...
The colon separated list is used to specify the precise credential
to be used for remote access by root.
The elements of the list may be either names or numbers.
Note that user: should be used to distinguish a credential containing
no groups from a complete credential for that user.
.Fl mapall No = Sy user:group1:group2:...
specifies a mapping for all client uids (including root)
using the same semantics as
in an effort to be backward compatible with older export file formats.
options, remote accesses by root will result in using a credential of -2:-2.
All other users will be mapped to their remote credential.
remote access by root will be mapped to that credential instead of -2:-2.
all users (including root) will be mapped to that credential in
option specifies that the Kerberos authentication server should be
used to authenticate and map client credentials.
(Note that this is NOT Sun NFS compatible and
is supported for TCP transport only.)
option specifies that the filesystem should be exported read-only
in an effort to be backward compatible with older export file formats.
The third component of a line specifies the host set to which the line applies.
The set may be specified in three ways.
The first way is to list the host name(s) separated by white space.
(Standard internet ``dot'' addresses may be used in place of names.)
The second way is to specify a ``netgroup'' as defined in the netgroup file (see
The third way is to specify an internet subnetwork using a network and
network mask that is defined as the set of all hosts with addresses within
This latter approach requires less overhead within the
kernel and is recommended for cases where the export line refers to a
large number of clients within an administrative subnet.
The first two cases are specified by simply listing the name(s) separated
All names are checked to see if they are ``netgroup'' names
first and are assumed to be hostnames otherwise.
Using the full domain specification for a hostname can normally
circumvent the problem of a host that has the same name as a netgroup.
The third case is specified by the flag
.Fl network No = Sy netname
.Fl mask No = Sy netmask .
If the mask is not specified, it will default to the mask for that network
.Bd -literal -offset indent
/usr /usr/local -maproot=0:10 friends
/usr -maproot=daemon grumpy.cis.uoguelph.ca 131.104.48.16
/u -maproot=bin: -network 131.104.48 -mask 255.255.255.0
/u2 -maproot=root friends
/u2 -alldirs -kerb -network cis-net -mask cis-mask
local filesystem mount points, the above example specifies the following:
where friends is specified in the netgroup file
with users mapped to their remote credentials and
root mapped to uid 0 and group 10.
It is exported read-write and the hosts in ``friends'' can mount either /usr
.Em grumpy.cis.uoguelph.ca
with users mapped to their remote credentials and
root mapped to the user and groups associated with ``daemon'';
it is exported to the rest of the world as read-only with
all users mapped to the user and groups associated with ``nobody''.
is exported to all hosts on the subnetwork
with root mapped to the uid for ``bin'' and with no group access.
is exported to the hosts in ``friends'' with root mapped to uid and groups
associated with ``root'';
it is exported to all hosts on network ``cis-net'' allowing mounts at any
directory within /u2 and mapping all uids to credentials for the principal
that is authenticated by a Kerberos ticket.
.Bl -tag -width /etc/exports -compact
The default remote mount-point file.
The export options are tied to the local mount points in the kernel and
must be non-contradictory for any exported subdirectory of the local
It is recommended that all exported directories within the same server
filesystem be specified on adjacent lines going down the tree.
You cannot specify a hostname that is also the name of a netgroup.
Specifying the full domain specification for a hostname can normally