ZyXEL Communications P660HW-DX V2 - V3.40 User Manual page 15

9.4.2 Types of DoS Attacks ............................................................................................... 146
9.5 Stateful Inspection ............................................................................................................. 148
9.5.1 Stateful Inspection Process ...................................................................................... 149
9.5.2 Stateful Inspection and the ZyXEL Device ............................................................... 150
9.5.3 TCP Security ............................................................................................................ 150
9.5.4 UDP/ICMP Security .................................................................................................. 151
9.5.5 Upper Layer Protocols ............................................................................................. 151
9.6 Guidelines for Enhancing Security with Your Firewall ....................................................... 152
9.6.1 Security In General .................................................................................................. 152
9.7 Packet Filtering Vs Firewall ............................................................................................... 153
9.7.1 Packet Filtering: ....................................................................................................... 153
9.7.2 Firewall ..................................................................................................................... 153
Chapter 10
Firewall Configuration .......................................................................................................... 155
10.1 Access Methods .............................................................................................................. 155
10.2 Firewall Policies Overview ............................................................................................... 155
10.3 Rule Logic Overview ........................................................................................................ 156
10.3.1 Rule Checklist ........................................................................................................ 156
10.3.2 Security Ramifications ............................................................................................ 156
10.3.3 Key Fields For Configuring Rules ......................................................................... 157
10.4 Connection Direction ....................................................................................................... 157
10.4.1 LAN to WAN Rules ................................................................................................. 158
10.4.2 Alerts ...................................................................................................................... 158
10.5 General Firewall Policy
10.6 Firewall Rules Summary ................................................................................................. 159
10.6.1 Configuring Firewall Rules ................................................................................... 161
10.6.2 Customized Services ............................................................................................ 164
10.6.3 Configuring a Customized Service ....................................................................... 164
10.7 Example Firewall Rule ..................................................................................................... 165
10.8 Predefined Services ........................................................................................................ 169
10.9 Anti-Probing ..................................................................................................................... 171
10.10 DoS Thresholds ............................................................................................................ 172
10.10.1 Threshold Values ................................................................................................. 172
10.10.2 Half-Open Sessions ............................................................................................. 173
10.10.3 Configuring Firewall Thresholds ........................................................................... 173
Chapter 11
Content Filtering ................................................................................................................... 177
11.1 Content Filtering Overview .............................................................................................. 177
11.2 Configuring Keyword Blocking ........................................................................................ 177
11.3 Configuring the Schedule ................................................................................................ 178
11.4 Configuring Trusted Computers ...................................................................................... 179
P-660HW-Dx v2 User's Guide
................................................................................................. 158
Table of Contents
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