Figure 13-7 Configuring A Pop Custom Port - ZyXEL Communications ZyXEL ZyWALL 50 User Manual

ZyWALL 100 Internet Security Gateway
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.
Type a name for this
custom port and select TCP
service.
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
13-8
Click Single and enter
a port number of 110.

Figure 13-7 Configuring A POP Custom Port

Click Apply when
you've finished.
Example Firewall Rules