ZyXEL Communications P-2802H-I Series, User Manual

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Table of Contents
P-2802H(W)(L)-I Series User’s Guide
15
10.16 PSTN Line Screen (“L” models only) ............................................................................ 152
Chapter 11
Firewalls................................................................................................................................. 155
11.1 Firewall Overview ............................................................................................................. 155
11.1.1 Stateful Inspection Firewall ..................................................................................... 155
11.1.2 About the ZyXEL Device Firewall ........................................................................... 155
11.1.3 Guidelines For Enhancing Security With Your Firewall .......................................... 156
11.2 General Firewall Policy Overview ................................................................................... 156
11.3 Security Considerations ................................................................................................... 158
11.4 Triangle Route ................................................................................................................. 158
11.4.1 The “Triangle Route” Problem ................................................................................ 158
11.4.2 Solving the “Triangle Route” Problem .................................................................... 159
11.5 General Firewall Policy ................................................................................................... 160
11.6 Firewall Rules Summary ................................................................................................. 161
11.6.1 Configuring Firewall Rules ................................................................................... 163
11.6.2 Customized Services ............................................................................................. 166
11.6.3 Configuring A Customized Service ....................................................................... 166
11.7 Example Firewall Rule ..................................................................................................... 167
11.8 Firewall Thresholds ......................................................................................................... 171
11.8.1 Threshold Values .................................................................................................... 172
11.8.2 Configuring Firewall Thresholds ............................................................................. 172
Chapter 12
Content Filtering ................................................................................................................... 175
12.1 Content Filtering Overview ............................................................................................. 175
12.2 Configuring Keyword Blocking ....................................................................................... 175
12.3 Configuring the Schedule .............................................................................................. 176
12.4 Configuring Trusted Computers ..................................................................................... 177
Chapter 13
Introduction to IPSec............................................................................................................ 179
13.1 VPN Overview ................................................................................................................. 179
13.1.1 IPSec ...................................................................................................................... 179
13.1.2 Security Association ............................................................................................... 179
13.1.3 Other Terminology .................................................................................................. 179
13.1.4 VPN Applications ................................................................................................... 180
13.2 IPSec Architecture ........................................................................................................... 180
13.2.1 IPSec Algorithms .................................................................................................... 181
13.2.2 Key Management ................................................................................................... 181
13.3 Encapsulation .................................................................................................................. 181
13.3.1 Transport Mode ...................................................................................................... 182
13.3.2 Tunnel Mode ......................................................................................................... 182