Table of Contents
P-660H-Tx v2 User’s Guide
14
Chapter
8
Firewalls
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111
8.1 Firewall Overview
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111
8.2 Types of Firewalls
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111
8.2.1 Packet Filtering Firewalls
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111
8.2.2 Application-level Firewalls
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112
8.2.3 Stateful Inspection Firewalls
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112
8.3 Introduction to ZyXEL’s Firewall
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112
8.3.1 Denial of Service Attacks
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113
8.4 Denial of Service
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113
8.4.1 Basics
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113
8.4.2 Types of DoS Attacks
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114
8.5 Stateful Inspection
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116
8.5.1 Stateful Inspection Process
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117
8.5.2 Stateful Inspection and the ZyXEL Device
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118
8.5.3 TCP Security
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118
8.5.4 UDP/ICMP Security
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119
8.5.5 Upper Layer Protocols
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119
8.6 Guidelines for Enhancing Security with Your Firewall
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120
8.6.1 Security In General
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120
8.7 Packet Filtering Vs Firewall
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121
8.7.1 Packet Filtering:
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121
8.7.2 Firewall
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121
Chapter
9
Firewall Configuration
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123
9.1 Access Methods
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123
9.2 Firewall Policies Overview
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123
9.3 Rule Logic Overview
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124
9.3.1 Rule Checklist
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124
9.3.2 Security Ramifications
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124
9.3.3 Key Fields For Configuring Rules
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125
9.4 Connection Direction
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125
9.4.1 LAN to WAN Rules
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126
9.4.2 Alerts
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126
9.5 General Firewall Policy
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126
9.6 Firewall Rules Summary
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127
9.6.1 Configuring Firewall Rules
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129
9.6.2 Customized Services
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132
9.6.3 Configuring a Customized Service
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132
9.7 Example Firewall Rule
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133
9.8 Predefined Services
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137
9.9 Anti-Probing
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139