ZyXEL Communications P-660HW-Tx v3 User Manual page 15

10.4.2 Port Forwarding: Services and Port Numbers ........................................................ 152
10.4.3 Configuring Servers Behind Port Forwarding (Example) ....................................... 152
10.5 Configuring Port Forwarding ........................................................................................... 153
10.5.1 Port Forwarding Rule Edit ..................................................................................... 154
Part IV: Security ................................................................................... 157
Chapter 11
Firewalls................................................................................................................................. 159
11.1 Firewall Overview ............................................................................................................ 159
11.2 Types of Firewalls ............................................................................................................ 159
11.2.1 Packet Filtering Firewalls ....................................................................................... 159
11.2.2 Application-level Firewalls ...................................................................................... 160
11.2.3 Stateful Inspection Firewalls ................................................................................... 160
11.3 Introduction to ZyXEL's Firewall ....................................................................................... 160
11.3.1 Denial of Service Attacks ....................................................................................... 161
11.4 Denial of Service .............................................................................................................. 161
11.4.1 Basics ..................................................................................................................... 161
11.4.2 Types of DoS Attacks ............................................................................................. 162
11.5 Stateful Inspection ............................................................................................................ 164
11.5.1 Stateful Inspection Process .................................................................................... 165
11.5.2 Stateful Inspection and the ZyXEL Device ............................................................. 166
11.5.3 TCP Security .......................................................................................................... 166
11.5.4 UDP/ICMP Security ................................................................................................ 167
11.5.5 Upper Layer Protocols ............................................................................................ 167
11.6 Guidelines for Enhancing Security with Your Firewall ...................................................... 168
11.6.1 Security In General ................................................................................................. 168
11.7 Packet Filtering Vs Firewall .............................................................................................. 169
11.7.1 Packet Filtering: ...................................................................................................... 169
11.7.2 Firewall ................................................................................................................... 169
11.8 Triangle Route ................................................................................................................. 170
11.8.1 The "Triangle Route" Problem ................................................................................ 170
11.8.2 The "Triangle Route" Solutions ............................................................................... 171
Chapter 12
Firewall Configuration .......................................................................................................... 173
12.1 Access Methods .............................................................................................................. 173
12.2 Firewall Policies Overview ............................................................................................... 173
12.3 Rule Logic Overview ........................................................................................................ 174
12.3.1 Rule Checklist ........................................................................................................ 174
12.3.2 Security Ramifications ............................................................................................ 174
P-660HW-Tx v3 User's Guide
Table of Contents
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