ZyXEL Communications Prestige 660H Series User Manual page 11

12.2.1 Packet Filtering Firewalls ......................................................................130
12.2.2 Application-level Firewalls ....................................................................130
12.2.3 Stateful Inspection Firewalls ................................................................131
12.3 Introduction to ZyXEL's Firewall .....................................................................131
12.3.1 Denial of Service Attacks ......................................................................132
12.4 Denial of Service ............................................................................................132
12.4.1 Basics ...................................................................................................132
12.4.2 Types of DoS Attacks ...........................................................................133
12.4.2.1 ICMP Vulnerability ......................................................................135
12.4.2.2 Illegal Commands (NetBIOS and SMTP) ....................................135
12.4.2.3 Traceroute ...................................................................................136
12.5 Stateful Inspection ..........................................................................................136
12.5.1 Stateful Inspection Process ..................................................................137
12.5.2 Stateful Inspection and the Prestige .....................................................138
12.5.3 TCP Security .........................................................................................138
12.5.4 UDP/ICMP Security ..............................................................................139
12.5.5 Upper Layer Protocols ..........................................................................139
12.6 Guidelines for Enhancing Security with Your Firewall ....................................139
12.6.1 Security In General ...............................................................................140
12.7 Packet Filtering Vs Firewall ............................................................................141
12.7.1 Packet Filtering: ....................................................................................141
12.7.1.1 When To Use Filtering .................................................................141
12.7.2 Firewall .................................................................................................141
12.7.2.1 When To Use The Firewall ..........................................................141
Chapter 13
Firewall Configuration ......................................................................................... 144
13.1 Access Methods .............................................................................................144
13.2 Firewall Policies Overview .............................................................................144
13.3 Rule Logic Overview ......................................................................................145
13.3.1 Rule Checklist .......................................................................................145
13.3.2 Security Ramifications ..........................................................................145
13.3.3 Key Fields For Configuring Rules .........................................................146
13.3.3.1 Action ..........................................................................................146
13.3.3.2 Service ........................................................................................146
13.3.3.3 Source Address ...........................................................................146
13.3.3.4 Destination Address ....................................................................146
13.4 Connection Direction Example .......................................................................146
13.4.1 LAN to WAN Rules ...............................................................................147
13.4.2 WAN to LAN Rules ...............................................................................147
13.4.3 Alerts .....................................................................................................148
13.5 Configuring Basic Firewall Settings ................................................................148
13.6 Rule Summary ...............................................................................................149
Prestige 660H/HW Series User's Guide
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