exports(4)						     Kernel Interfaces Manual							exports(4)

NAME

       exports - Defines remote mount points for NFS mount requests

SYNOPSIS

       /etc/exports

DESCRIPTION

       The  exports file specifies remote mount points for the NFS mount protocol per the NFS server specification (see Network File System Proto-
       col Specification, RFC1094).

       Each entry in the /etc/exports file consists of a filesystem or directory name followed by an optional list of options or an optional  list
       of  identifiers	or  both.  The	identifiers  define which remote hosts can mount that particular filesystem or directory.  The identifiers
       listed beside the name of each filesystem or directory can be either host names, IP addresses, or NIS netgroups names.  If  no  identifiers
       are listed, the entry is exported to all hosts.

       A backslash character () in the right-most position of a line indicates line continuation.  A number sign (#) either at the beginning of a
       line or at the end of a syntax line marks a comment that extends to the end of that line.  You cannot use a number sign at  the	end  of  a
       line containing a backslash character because the backslash nullifies the end of line character.

       Note  that  the	mount command will touch the /etc/exports file when issued with the -t nfs option.  If you create a new /etc/exports file,
       you should ensure that its ownership is equivalent to that of the default, which is; bin:bin (3:4).

       The format of the exports file is as follows:

       pathname [option ...] [identifier ...]

       #comments

       The pathname specifies the name of a mounted local filesystem or a directory of a mounted local filesystem.  The  pathname  must  begin	in
       column 1.

       The  following are valid export file options: Maps client superuser access to uid 0 for all hosts mounting this path.  If you want to allow
       client superusers access to the filesystem or directory with the same permissions as a local superuser, use -root=0.  Use -root=0  only	if
       you  trust  the superuser on the client system.	The default is for client superusers to be mapped to uid -2, which maps a client superuser
       to nobody.  This limits access to world accessible files.  If both the -root=0 option and the -anon=uid option are used,  the  root  option
       overrides  the  uid  specified in anon for client superusers.  Maps the client superusers on the specified hosts only to uid 0.	The format
       for the hostlist argument is as follows:

       client[:client]...

       The client specification can be a host name or IP address.  By default, client superusers are mapped to -2.  This option overrides the  uid
       specified  in  -anon=uid  for  client superusers in hostlist.  Maps anonymous users to the specified uid.  Client superusers are considered
       anonymous by the NFS server, as are requests that come in without UNIX authentication.  By default, anonymous users are mapped to  uid  -2.
       Setting anon to -1 disables anonymous access.  The filesystem or directory is exported read-only (default is read-write).  The -o option is
       a synonym for -ro for backward compatibility.  limits read-write access to the hosts specified.	All other hosts allowed to mount this path
       are granted read-only access.  The format for the hostlist argument is as follows:

       client[:client]...

       The  client specification can be a host name or IP address.  If both the -ro and -rw=hostlist options are specified, -rw prevails.  Exports
       a filesystem or directory for WebNFS public access.  Note that only one exported filesystem can have this option set.

									  Note
       When the -public option is set, the mount access list is ignored by the WebNFS server. This means that all hosts using the WebNFS  protocol
       have access to this directory.

       After setting the -public option, be sure to send the mountd process a HUP signal. See kill(1) for further information.
       Used  with  -public  option.  Enables  the server to look for an index.html file when given a directory name.  Specifies the hosts to grant
       mount access to.  The format for the hostlist argument is as follows:

       client[:client]...

       The client specification can be a host name, IP address, or NIS network group.  This option is provided for readability	and  compatibility
       with  certain  export file formats.  Alternatively, to identify the client systems who are allowed access to this export use the whitespace
       separated identifier list described below.

       The options can be applied to both file system and directory entries in /etc/exports.

       Alternatively, you can list options using only one leading dash and separating them with commas as in -option[,option]....

       You use the identifier field to specify host names, network groups, or both, separated by white space that specify the access list for this
       export.	 Host  names  can optionally contain the local BIND domain name.  A whitespace character in the left-most position of a line indi-
       cates line continuation.

									  Note
       If no hosts or netgroups are specified, the mount daemon exports this file system or directory to anyone requesting it.	See the  mountd(8)
       reference page for information on how to limit this scope to known hosts or to hosts in the same BIND domain.

       For example, suppose you enter:

       /usr   -root=0	milan	kuan_yin.cis.berkeley.edu   /usr/local	 555.555.55.55	 /u2   -ro   /u3/dir1  -rw=milan:venice:florence  /u3/dir2
       -root=milan,access=venice:florence  /u3/dir3  -root=0,access=milan:venice:florence  /u3/dir4  -root=0  milan   venice   florence   /u3/dir5
       -root=milan -anon=-1 /u3/dir6 -ro -public milan venice florence

       If  /usr,  /u2  and  /u3  are  local file system mount points, this specifies the following: /usr is exported read-write to hosts milan and
       kuan_yin.cis.berkeley.edu with root mapped to uid=0.  /usr/local is exported read-write to host 555.555.55.55 with root mapped to -2.  (For
       security  reasons,  this example uses the fictitious IP address 555.555.55.55.)	/u2 is exported to all hosts read-only with root mapped to
       -2.  /u3/dir1 is exported read-write to hosts milan, venice, and florence and read-only to all other hosts.  For all hosts, root is  mapped
       to  -2.	 /u3/dir2  is exported with root mapped to 0 to host milan.  Hosts milan, venice, and florence are allowed to mount this directory
       read-write.  Root on hosts venice and florence is mapped to -2.	/u3/dir3 is exported read-write and with root mapped to 0 to hosts  milan,
       venice,	and  florence.	 /u3/dir4  is  exported in the same manner as the previous example.  /u3/dir5 is exported read-write to all hosts.
       Anonymous users are not allowed to mount this directory, with the exception of the client superuser on host milan.  Root is mapped to 0	on
       host  milan  and  to  -2 on all other hosts.  /u3/dir6 Hosts milan, venice, and florence are allowed to mount this directory read-only. All
       other hosts have read-only WebNFS access, but cannot mount this directory.

       Each file system that you want to allow clients to mount must be explicitly defined.  Exporting only the root (/) will not allow clients to
       mount /usr.  Exporting only /usr will not allow clients to mount /usr/local, if it is a file system.

       Duplicate directory entries are not allowed.  The first entry is valid and following duplicates are ignored.

       Desired export options must be explicitly specified for each exported resource: file system or directory.  If a file system and subdirecto-
       ries within it are exported, the options associated with the file system are not ``inherited.''	You do not need to export an  entire  file
       system to allow clients to mount subdirectories within it.

       The  access  list  associated with each exported resource identifies which clients can mount that resource with the specified options.  For
       example, you can export an entire file system read-only, with a subdirectory within it exported read-write to a subset of  clients.   If  a
       client  that  is  not  identified in the export access list of a directory attempts to mount it, then access is checked against the closest
       exported ancestor.  If mount access is allowed at a higher level in the directory tree of the file system, the  export  options	associated
       with the successful match will be in effect.

       To  make  a  change  to	the exports file and have it take effect immediately, send the mountd process a HUP signal.  Otherwise, the mountd
       process will reread the exports file the next time it receives a mount request from an NFS client or a showmount -e request.

RELATED INFORMATION

       Daemons: mountd(8), nfsd(8)

       Commands: showmount(8)

       Files: hosts(4), netgroup(4)
       Network Administration delim off

																	exports(4)