ZyXEL Communications P-660HW-D User Manual page 14

Table of Contents
7.8 QoS Screen ....................................................................................................................... 120
7.8.1 ToS (Type of Service) and WMM QoS ..................................................................... 121
7.8.2 Application Priority Configuration ............................................................................. 122
Chapter 8
Network Address Translation (NAT) Screens..................................................................... 125
8.1 NAT Overview ................................................................................................................... 125
8.1.1 NAT Definitions ........................................................................................................ 125
8.1.2 What NAT Does ....................................................................................................... 126
8.1.3 How NAT Works ....................................................................................................... 126
8.1.4 NAT Application ........................................................................................................ 126
8.1.5 NAT Mapping Types ................................................................................................. 127
8.2 SUA (Single User Account) Versus NAT ........................................................................... 128
8.3 NAT General Setup ........................................................................................................... 128
8.4 Port Forwarding ................................................................................................................. 129
8.4.1 Default Server IP Address ........................................................................................ 130
8.4.2 Port Forwarding: Services and Port Numbers .......................................................... 130
8.4.3 Configuring Servers Behind Port Forwarding (Example) ......................................... 131
8.5 Configuring Port Forwarding ............................................................................................. 131
8.5.1 Port Forwarding Rule Edit ....................................................................................... 132
8.6 Address Mapping .............................................................................................................. 133
8.6.1 Address Mapping Rule Edit ..................................................................................... 135
Chapter 9
Firewalls................................................................................................................................. 137
9.1 Firewall Overview ............................................................................................................. 137
9.2 Types of Firewalls .............................................................................................................. 137
9.2.1 Packet Filtering Firewalls ......................................................................................... 137
9.2.2 Application-level Firewalls ........................................................................................ 138
9.2.3 Stateful Inspection Firewalls ..................................................................................... 138
9.3 Introduction to ZyXEL's Firewall ........................................................................................ 138
9.3.1 Denial of Service Attacks ......................................................................................... 139
9.4 Denial of Service ............................................................................................................... 139
9.4.1 Basics ....................................................................................................................... 139
9.4.2 Types of DoS Attacks ............................................................................................... 140
9.5 Stateful Inspection ............................................................................................................. 142
9.5.1 Stateful Inspection Process ...................................................................................... 143
9.5.2 Stateful Inspection and the ZyXEL Device ............................................................... 144
9.5.3 TCP Security ............................................................................................................ 144
9.5.4 UDP/ICMP Security .................................................................................................. 145
9.5.5 Upper Layer Protocols ............................................................................................. 145
9.6 Guidelines for Enhancing Security with Your Firewall ....................................................... 146
9.6.1 Security In General .................................................................................................. 146
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P-660HW-D User's Guide