The hosts that will have access to the exported directory.
Warning: when exporting with krb5, the choice of the clients is made in the configuration of Kerberos5.
Six ways of specifying which hosts are allowed to mount the directory are available:
- Everyone
- Any host capable of contacting your system is allowed access. This option
    should be used with care, especially if your system is connected to the
    Internet.
- Host(s)
- This can either be a single IP address, a single hostname, or a regular
    expression like *.foo.com. In the last case, any host whose
    reverse DNS lookup by IP address matches the expression will be allowed
    access.
- WebNFS clients
- Allows clients using Sun's WebNFS protocol to access this directory.
- NIS Netgroup
- Allows all members of the specified NIS netgroup to access this export.
- IPv4 Network and Netmask
- Any host in the specified subnet is allowed access. For example, if the
    network was 10.1.2.0 and the netmask 255.255.255.0,
    all hosts with IP addresses from 10.1.2.0 to 10.1.2.255
    would be allowed.
- IPv6 Address and Prefix
- Any host in the specified subnet is allowed access.