D-Link DFL-1500 [99/271] Demands

DFL-900/1500 User Manual Chapter 10

Firewall

Chapter 10

Firewall

This chapter introduces firewall and explains how to implement it.

10.1 Demands

1. Administrators detect that PC1_1 in LAN_1 is doing something that may hurt our company and should instantly block his

traffic towards the Internet.

2. On the Internet, a denial of service (DoS) attack is an incident in which a user or organization is deprived of the services of

a resource they would normally expect to have. Typically, the loss of service is the inability of a particular network service,

such as e-mail, to be available or the temporary loss of all network connectivity and services. In the worst cases, for

example, a Web site accessed by millions of people can occasionally be forced to temporarily cease operation. A denial of

service attack can also destroy programming and files in a computer system. Although usually intentional and malicious, a

denial of service attack can sometimes happen accidentally. A denial of service attack is a type of security breach to a

computer system that does not usually result in the theft of information or other security loss. However, these attacks can

cost the target person or company a great deal of time and money. Now, suppose a DMZ server was attacked by

SYN-Flooding attack and requires the DFL-1500 to protect it.

10.2 Objectives

1. Block the traffic from PC1_1 in LAN1 to the Internet in WAN1.

2. Start the SYN-Flooding protection.

Figure 10-1 Setting up the firewall rule

10.3 Methods

1. Configure the Address/Service/Schedule first.

2. Add a LAN1-to-WAN1 Firewall rule to block PC1_1.

3. Start the SYN-Flooding protection by detecting statistical half-open TCP connections.