ZyXEL Communications ZyWALL 10/10, User Manual

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ZyWALL 10/10 II/50 Internet Security Gateway
16-8 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.
POP3 is now a predefined service, but you still use the same process for
configuring a custom port.
Figure 16-7 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. Click Apply when
you’ve finished.
Click Single and enter
a port number of 110.