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ADSL2+ Modem Router DM111PSPv2 User Manual
3-2 Security and Firewall Protection
v1.0, December 2008
Before starting, you need to determine which type of protocol, service, application, or game you
will provide, and the IP address of the computer that will provide the service. Be sure that the
computer’s IP address never changes.
Firewall Rules (IP Filtering)
Firewall rules block or allow specific traffic (IP packets) passing through from one side of the
router to the other. Inbound rules (WAN to LAN) restrict access by outsiders to private resources,
selectively allowing only specific outside users to access specific resources. Outbound rules (LAN
to WAN) determine what outside resources local users can have access to.
The default inbound and outbound rules of the modem router are:
• Inbound. Block all access from outside except responses to requests from the LAN side.
• Outbound. Allow all access from the LAN side to the outside.
You can define additional rules that will specify exceptions to the default rules. By adding custom
rules, you can block or allow access based on protocol, source IP addresses, and destination IP
addresses.
Note: To assure that the same computer always has the same IP address, use the reserved
IP address feature. See
“Reserved IP Addresses” on page 4-4.
Warning: This feature is for advanced users only. Incorrect configuration may cause
serious Internet access problems.