TCP_WRAPPERS

syntax
<daemon list> : <client list> [except <client list>] [: <option>]


.example.com                            - anyone from example domain
192.168.190.                            - any ip from the 192.168.190.0 network
192.168.190.0/255.255.255.0  - any ip from the 192.168.190.0 network
ALL                                          - Anyone
user@computer                         - user from specific computer

Lookup Order
1./etc/hosts.allow
2./etc/hosts.deny
3.allow by default