ZyXEL Communications P-660HW-DX - page 15

Table of Contents
P-660HW-Dx User’s Guide 15
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 ...................................................................... ...........................158
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