ZyXEL Communications 50 User Manual
ZyWALL 100 Internet Security Gateway
13-8
Example Firewall Rules
Step 3. Now you want to restrict access to the Internet except for the HTTP proxy server and your mail
server. First you need to create a custom port for POP3. POP (Post Office Protocol) is an Internet
mail server protocol that provides an incoming message storage system. It works in conjunction
with the SMTP (Simple Mail Transfer Protocol), which provides the message transport services
required to move mail from one system to another. The current version is called POP3. Click
Custom Ports and then click Edit. Configure the screen as follows.
mail server protocol that provides an incoming message storage system. It works in conjunction
with the SMTP (Simple Mail Transfer Protocol), which provides the message transport services
required to move mail from one system to another. The current version is called POP3. Click
Custom Ports and then click Edit. Configure the screen as follows.
Figure 13-7 Configuring A POP Custom Port
Step 4. Now, you will create rules to block all outgoing traffic (from the local network to the Internet)
except for traffic originating from the HTTP proxy server and our mail server. Click Local
Type a name for this
custom port and select TCP
service.
custom port and select TCP
service.
Click Apply when
you’ve finished.
you’ve finished.
Click Single and enter
a port number of 110.
a port number of 110.