9

Firewall

9.1 Overview

This chapter shows you how to enable and configure the P-870HN-51D firewall settings.

The P-870HN-51D firewall is a packet filtering firewall and restricts access based on the source/destination computer network address of a packet and the type of application.

9.1.1 What You Can Do in this Chapter

The Incoming screen lets you view and configure incoming IP filtering rules (Section 9.3 on page 142).

9.2 What You Need to Know

The following terms and concepts may help as you read through this chapter.

Basics

Computers share information over the Internet using a common language called TCP/IP. TCP/IP, in turn, is a set of application protocols that perform specific functions. An “extension number”, called the "TCP port" or "UDP port" identifies these protocols, such as HTTP (Web), FTP (File Transfer Protocol), POP3 (E-mail), etc. For example, Web traffic by default uses TCP port 80.

When computers communicate on the Internet, they are using the client/server model, where the server "listens" on a specific TCP/UDP port for information requests from remote client computers on the network. For example, a Web server typically listens on port 80. Please note that while a computer may be intended for use over a single port, such as Web on port 80, other ports are also active. If the person configuring or managing the computer is not careful, a hacker could attack it over an unprotected port.

 

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P-870HN-51D User’s Guide