ZyXEL P-870MH-C1 User Guide - Page 164

Chapter 10 Firewall Some of the most common IP ports are: Table 49 Common IP Ports 21 FTP 53 23 Telnet 80 25 SMTP 110 DNS HTTP POP3 Default Filtering Policies Filtering rules are grouped based on the direction of travel of packets to which they apply. The default rule for incoming traffic blocks all incoming connections from the WAN to the LAN. If you wish to allow certain WAN users to have access to your LAN, you will need to create custom rules to allow it. Note: If you configure filtering rules without a good understanding of how they work, you might inadvertently introduce security risks to the firewall and to the protected network. Make sure you test your rules after you configure them. These custom rules work by comparing the Source IP address, Destination IP address and IP protocol type of network traffic to rules set by the administrator. Your customized rules take precedence and override the Device's default rules. 10.3 The Firewall Screen Click Security > Firewall > Incoming to display the following screen. This screen displays a list of the configured incoming filtering rules. Figure 81 Firewall > Incoming 164 P-870HN-5xb User's Guide