ZyXEL Communications Prestige 662H Series User Manual page 12

Chapter 12
Time and Date....................................................................................................... 142
12.1 Configuring Time and Date ............................................................................142
Chapter 13
Firewalls................................................................................................................ 144
13.1 Firewall Overview ...........................................................................................144
13.2 Types of Firewalls ..........................................................................................144
13.2.1 Packet Filtering Firewalls ......................................................................144
13.2.2 Application-level Firewalls ....................................................................144
13.2.3 Stateful Inspection Firewalls ................................................................145
13.3 Introduction to ZyXEL's Firewall .....................................................................145
13.3.1 Denial of Service Attacks ......................................................................146
13.4 Denial of Service ............................................................................................146
13.4.1 Basics ...................................................................................................146
13.4.2 Types of DoS Attacks ...........................................................................147
13.4.2.1 ICMP Vulnerability ......................................................................149
13.4.2.2 Illegal Commands (NetBIOS and SMTP) ....................................149
13.4.2.3 Traceroute ...................................................................................150
13.5 Stateful Inspection ..........................................................................................150
13.5.1 Stateful Inspection Process ..................................................................151
13.5.2 Stateful Inspection and the Prestige .....................................................152
13.5.3 TCP Security .........................................................................................152
13.5.4 UDP/ICMP Security ..............................................................................153
13.5.5 Upper Layer Protocols ..........................................................................153
13.6 Guidelines for Enhancing Security with Your Firewall ....................................154
13.6.1 Security In General ...............................................................................154
13.7 Packet Filtering Vs Firewall ............................................................................155
13.7.1 Packet Filtering: ....................................................................................155
13.7.1.1 When To Use Filtering .................................................................155
13.7.2 Firewall .................................................................................................155
13.7.2.1 When To Use The Firewall ..........................................................156
Chapter 14
Firewall Configuration ......................................................................................... 158
14.1 Access Methods .............................................................................................158
14.2 Firewall Policies Overview .............................................................................158
14.3 Rule Logic Overview ......................................................................................159
14.3.1 Rule Checklist .......................................................................................159
14.3.2 Security Ramifications ..........................................................................160
14.3.3 Key Fields For Configuring Rules .........................................................160
14.3.3.1 Action ..........................................................................................160
14.3.3.2 Service ........................................................................................160
Prestige 662H/HW Series User's Guide
12