Table of Contents
P-662H/HW-D Series User’s Guide
15
10.2 Types of Firewalls
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157
10.2.1 Packet Filtering Firewalls
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157
10.2.2 Application-level Firewalls
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158
10.2.3
Stateful Inspection Firewalls
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158
10.3 Introduction to ZyXEL’s Firewall
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158
10.3.1 Denial of Service Attacks
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159
10.4 Denial of Service
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159
10.4.1 Basics
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159
10.4.2 Types of DoS Attacks
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160
10.5 Stateful Inspection
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162
10.5.1 Stateful Inspection Process
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163
10.5.2 Stateful Inspection and the ZyXEL Device
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164
10.5.3 TCP Security
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164
10.5.4 UDP/ICMP Security
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165
10.5.5 Upper Layer Protocols
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165
10.6 Guidelines for Enhancing Security with Your Firewall
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166
10.6.1 Security In General
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166
10.7 Packet Filtering Vs Firewall
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167
10.7.1 Packet Filtering:
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167
10.7.2 Firewall
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167
Chapter
11
Firewall Configuration
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169
11.1 Access Methods
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169
11.2 Firewall Policies Overview
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169
11.3 Rule Logic Overview
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170
11.3.1 Security Ramifications
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170
11.3.2 Key Fields For Configuring Rules
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171
11.4 Connection Direction
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171
11.4.1 LAN to WAN Rules
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172
11.4.2 Alerts
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172
11.5 General Firewall Policy
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172
11.6 Firewall Rules Summary
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173
11.6.1 Configuring Firewall Rules
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175
11.6.2 Customized Services
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178
11.6.3 Configuring A Customized Service
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178
11.7 Example Firewall Rule
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179
11.8 Predefined Services
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183
11.9 Anti-Probing
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185
11.10 DoS Thresholds
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186
11.10.1 Threshold Values
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186
11.10.2 Half-Open Sessions
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187
11.10.3 Configuring Firewall Thresholds
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187