Example 1:
(192.168.123.100-192.168.123.149) They are allowed to send mail (port 25), receive mail (port 110), and browse Internet (port 80); port 53 (DNS) is necessary to resolve the domain name.
(192.168.123.10-192.168.123.20) They can do everything (block nothing) Others are all blocked.
Example 2:
