hosts_options

hosts_options – host access control language extensions

 

daemon_list : client_list : option : option …

 

allow
deny
Grant (deny) service. These options must appear at the end of a rule.

The allow and deny keywords make it possible to keep all access control rules within a single file, for example in the hosts.allow file.

To permit access from specific hosts only:
ALL: .friendly.domain: ALLOW
ALL: ALL: DENY

To permit access from all hosts except a few trouble makers:
ALL: .bad.domain: DENY
ALL: ALL: ALLOW

Notice the leading dot on the domain name patterns.