Operation Manual

For source or destination port, you can define a single port (80) or a
range of ports (1000-1999). Add prefix "T" or "U" to specify TCP or UDP
protocol. For example, T80, U53, U2000-2999. No prefix indicates both
TCP and UDP are defined. An empty implies all port addresses. Packet
Filter can work with Scheduling Rules, and give user more flexibility
on Access control. For Detail, please refer to Scheduling Rule.
Each rule can be enabled or disabled individually.
4.5.2.1 Inbound Filter:
To enable Inbound Packet Filter click the Inbound filter button and
check box next to Enable in the Inbound Packet Filter field.
Suppose you have SMTP Server (25), POP Server (110), Web Server
(80), FTP Server (21), and News Server (119) defined in Virtual Server
or DMZ Host.
Example 1
(1.2.3.100-1.2.3.149) They are allow to send mail (port 25), receive
mail (port 110), and browse the Internet (port 80)
(1.2.3.10-1.2.3.20) They can do everything (block nothing)
Others are all blocked.
Example 2