Gnet IP104 User Manual page 33

For source or destination IP address, you can define a single IP address (4.3.2.1) or a range of IP
addresses (4.3.2.1-4.3.2.254). An empty implies all IP addresses.
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.
Each rule can be enabled or disabled individually.
Inbound Filter:
To enable Inbound Packet Filter click the 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)