Table of Contents
P-660HWP-Dx User’s Guide 39
Part IV: Security ...................................................................................155

Chapter 10

Firewalls.................................................................................................................................157

10.1 Firewall Overview ............ ............................................................................................... 157
10.2 Types of Firewalls ............................................................................................................ 157
10.2.1 Packet Filtering Firewalls .................. ..................................................................... 157
10.2.2 Application-level Firewalls ...................................................................................... 158
10.2.3 Stateful Inspection Firewalls ................................................................................... 158
10.3 Introduction to ZyXEL’s Firewall ........................................ .............................................. 158
10.3.1 Denial of Service Attacks ............... ........................................................................ 159
10.4 Denial of Service ............................................................................................................. 159
10.4.1 Basics ..................................................................................................................... 159
10.4.2 Types of DoS Attacks ............................................................................................. 160
10.5 Stateful Inspection ...................................................... ..................................................... 162
10.5.1 Stateful Inspection Process .................................................................................... 163
10.5.2 Stateful Inspection and the P-660HWP-Dx .............................................. ..............164
10.5.3 TCP Security ............................................................ .............................................. 164
10.5.4 UDP/ICMP Security ................................................................................................ 165
10.5.5 Upper Layer Protocols ........................................................................................... 165
10.6 Guidelines for Enhancing Security with Your Firewall ............................. ........................166
10.6.1 Security In General ................................................................................................ 166
10.7 Packet Filtering Vs Firewall ............................................................................................. 167
10.7.1 Packet Filtering: ..................................................................................................... 167
10.7.2 Firewall .................................................................................................. .................167

Chapter 11

Firewall Configuration..........................................................................................................169

11.1 Access Methods ............................................................................................................... 169
11.2 Firewall Policies Overview .......................................................................... ..................... 169
11.3 Rule Logic Overview ........................................................................................................ 170
11.3.1 Rule Checklist ......................... ............................................................................... 170
11.3.2 Security Ramifications ............................................................................................ 170
11.3.3 Key Fields For Configuring Rules .......................................................................... 171
11.4 Connection Direction ........................................................................................................ 171
11.4.1 LAN to WAN Rules ................................................................................................. 172
11.4.2 Alerts .............................................................. ........................................................ 172
11.5 General Firewall Policy ............................................................................ .....................172
11.6 Firewall Rules Summary ................................................................................................. 173
11.6.1 Configuring Firewall Rules ........................ ........................................................... 175
11.6.2 Customized Services ............................................................................................. 178
11.6.3 Configuring a Customized Service ....................................................................... 178
11.7 Example Firewall Rule .................................................................................... .................179