-.TH EXPORTS 5 "4 March 2005" "Linux" "Linux File Formats Manual"
+.\"@(#)exports.5"
+.\"
+.TH exports 5 "31 December 2009"
.SH NAME
-exports \- NFS file systems being exported (for Kernel based NFS)
-.SH SYNOPSIS
-.B /etc/exports
+exports \- NFS server export table
.SH DESCRIPTION
The file
.I /etc/exports
-serves as the access control list for file systems which may be
-exported to NFS clients. It is used by
-.IR exportfs (8)
+contains a table of local physical file systems on an NFS server
+that are accessible to NFS clients.
+The contents of the file are maintained by the server's system
+administrator.
+.PP
+Each file system in this table has a list of options and an
+access control list.
+The table is used by
+.BR exportfs (8)
to give information to
-.IR mountd (8)
-and to the kernel based NFS file server daemon
-.IR nfsd (8).
+.BR mountd (8).
.PP
The file format is similar to the SunOS
.I exports
the export name using a backslash followed by the character code as three
octal digits.
.PP
-To apply changes to this file, run exportfs \-ra or restart the NFS server.
+To apply changes to this file, run
+.BR exportfs \-ra
+or restart the NFS server.
.PP
.SS Machine Name Formats
NFS clients may be specified in a number of ways:
as
.IR address/netmask
where the netmask can be specified in dotted-decimal format, or as a
-contiguous mask length (for example, either `/255.255.252.0' or `/22' appended
-to the network base address result in identical subnetworks with 10 bits of
-host). Wildcard characters generally do not work on IP addresses, though they
+contiguous mask length.
+For example, either `/255.255.252.0' or `/22' appended
+to the network base IPv4 address results in identical subnetworks with 10 bits of
+host. Wildcard characters generally do not work on IP addresses, though they
may work by accident when reverse DNS lookups fail.
'''.TP
'''.B =public
this way are ro, rw, no_root_squash, root_squash, and all_squash.
.PP
.SS General Options
-.IR exportfs
+.BR exportfs
understands the following export options:
.TP
.IR secure "\*d
above).
In releases of nfs-utils up to and including 1.0.0, this option was the
-default. In all subsequence releases,
+default. In all releases after 1.0.0,
.I sync
is the default, and
.I async
must be explicitly requested if needed.
-To help make system administrators aware of this change, 'exportfs'
+To help make system administrators aware of this change,
+.B exportfs
will issue a warning if neither
.I sync
nor
option is currently only effective on
.I "single host
exports. It does not work reliably with netgroup, subnet, or wildcard
-exports.
+exports.
This option can be very useful in some situations, but it should be
used with due care, and only after confirming that the client system
that option in the
.B exports
file. If you put neither option,
-.I exportfs
+.B exportfs
will warn you that the change is pending.
.TP
.TP
.IR no_acl
On some specially patched kernels, and when exporting filesystems that
-support ACLs, this option tells nfsd not to reveal ACLs to clients, so
+support ACLs, this option tells
+.B nfsd
+not to reveal ACLs to clients, so
they will see only a subset of actual permissions on the given file
system. This option is safe for filesystems used by NFSv2 clients and
old NFSv3 clients that perform access decisions locally. Current
.SS User ID Mapping
.PP
-.I nfsd
+.B nfsd
bases its access control to files on the server machine on the uid and
gid provided in each NFS RPC request. The normal behavior a user would
expect is that she can access her files on the server just as she would
.IR no_root_squash .
.PP
By default,
-'''.I nfsd
+'''.B nfsd
'''tries to obtain the anonymous uid and gid by looking up user
'''.I nobody
'''in the password file at startup time. If it isn't found, a uid and gid
-.I exportfs
+.B exportfs
chooses a uid and gid
of 65534 for squashed access. These values can also be overridden by
the
.IR anonuid " and " anongid
options.
'''.PP
-'''In addition to this,
-'''.I nfsd
+'''In addition to this,
+'''.B nfsd
'''lets you specify arbitrary uids and gids that should be mapped to user
'''nobody as well.
Finally, you can map all user requests to the
Map requests from uid/gid 0 to the anonymous uid/gid. Note that this does
not apply to any other uids or gids that might be equally sensitive, such as
user
-.IR bin
+.IR bin
or group
.IR staff .
.TP
.IR all_squash
Map all uids and gids to the anonymous user. Useful for NFS-exported
public FTP directories, news spool directories, etc. The opposite option
-is
+is
.IR no_all_squash ,
which is the default setting.
.TP
/projects proj*.local.domain(rw)
/usr *.local.domain(ro) @trusted(rw)
/home/joe pc001(rw,all_squash,anonuid=150,anongid=100)
-/pub (ro,insecure,all_squash)
+/pub *(ro,insecure,all_squash)
/srv/www \-sync,rw server @trusted @external(ro)
'''/pub/private (noaccess)
.fi
entry for the PC/NFS client discussed above. Line 5 exports the
public FTP directory to every host in the world, executing all requests
under the nobody account. The
-.I insecure
+.I insecure
option in this entry also allows clients with NFS implementations that
don't use a reserved port for NFS.
The sixth line exports a directory read-write to the machine 'server'
'''access to the private directory.
'''.SH CAVEATS
'''Unlike other NFS server implementations, this
-'''.I nfsd
+'''.B nfsd
'''allows you to export both a directory and a subdirectory thereof to
-'''the same host, for instance
+'''the same host, for instance
'''.IR /usr " and " /usr/X11R6 .
'''In this case, the mount options of the most specific entry apply. For
-'''instance, when a user on the client host accesses a file in
+'''instance, when a user on the client host accesses a file in
'''.IR /usr/X11R6 ,
-'''the mount options given in the
-'''.I /usr/X11R6
+'''the mount options given in the
+'''.I /usr/X11R6
'''entry apply. This is also true when the latter is a wildcard or netgroup
'''entry.
.SH FILES
.BR showmount (8).
'''.SH DIAGNOSTICS
'''An error parsing the file is reported using syslogd(8) as level NOTICE from
-'''a DAEMON whenever nfsd(8) or mountd(8) is started up. Any unknown
+'''a DAEMON whenever
+'''.BR nfsd (8)
+'''or
+'''.BR mountd (8)
+'''is started up. Any unknown
'''host is reported at that time, but often not all hosts are not yet known
-'''to named(8) at boot time, thus as hosts are found they are reported
-'''with the same syslogd(8) parameters.
+'''to
+'''.BR named (8)
+'''at boot time, thus as hosts are found they are reported
+'''with the same
+'''.BR syslogd (8)
+'''parameters.
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