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Prestige 2602HW Series User’s Guide
12
13.2 Types of Firewalls ..........................................................................................149
13.2.1 Packet Filtering Firewalls ......................................................................149
13.2.2 Application-level Firewalls ....................................................................149
13.2.3 Stateful Inspection Firewalls ................................................................150
13.3 Introduction to ZyXEL’s Firewall .....................................................................150
13.3.1 Denial of Service Attacks ......................................................................151
13.4 Denial of Service ............................................................................................151
13.4.1 Basics ...................................................................................................151
13.4.2 Types of DoS Attacks ...........................................................................152
13.4.2.1 ICMP Vulnerability ......................................................................154
13.4.2.2 Illegal Commands (NetBIOS and SMTP) ....................................154
13.4.2.3 Traceroute ...................................................................................155
13.5 Stateful Inspection ..........................................................................................155
13.5.1 Stateful Inspection Process ..................................................................156
13.5.2 Stateful Inspection and the Prestige .....................................................157
13.5.3 TCP Security .........................................................................................157
13.5.4 UDP/ICMP Security ..............................................................................158
13.5.5 Upper Layer Protocols ..........................................................................158
13.6 Guidelines for Enhancing Security with Your Firewall ....................................159
13.6.1 Security In General ...............................................................................159
13.7 Packet Filtering Vs Firewall ............................................................................160
13.7.1 Packet Filtering: ....................................................................................160
13.7.1.1 When To Use Filtering .................................................................160
13.7.2 Firewall .................................................................................................160
13.7.2.1 When To Use The Firewall ..........................................................161
Chapter 14
Firewall Configuration ......................................................................................... 163
14.1 Access Methods .............................................................................................163
14.2 Firewall Policies Overview .............................................................................163
14.3 Rule Logic Overview ......................................................................................164
14.3.1 Rule Checklist .......................................................................................164
14.3.2 Security Ramifications ..........................................................................165
14.3.3 Key Fields For Configuring Rules .........................................................165
14.3.3.1 Action ..........................................................................................165
14.3.3.2 Service ........................................................................................165
14.3.3.3 Source Address ...........................................................................165
14.3.3.4 Destination Address ....................................................................165
14.4 Connection Direction Example .......................................................................165
14.4.1 LAN to WAN Rules ...............................................................................166
14.4.2 WAN to LAN Rules ...............................................................................166
14.4.3 Alerts .....................................................................................................167
14.5 Configuring Basic Firewall Settings ................................................................167