ZyXEL Communications ZyWALL 10/10, User Manual

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ZYWALL 10/10 II/50 Internet Security Gateway
Table of Contents xi
9.1.5 NAT Mapping Types.......................................................................................................... 9-4
9.2 Using NAT ................................................................................................................................. 9-6
9.2.1 SUA (Single User Account) Versus NAT .......................................................................... 9-6
9.2.2 Applying NAT.................................................................................................................... 9-6
9.3 NAT Setup.................................................................................................................................. 9-8
9.3.1 Address Mapping Sets........................................................................................................ 9-8
9.4 NAT Server Sets – Port Forwarding......................................................................................... 9-13
9.4.1 Configuring a Server behind NAT ................................................................................... 9-14
9.5 General NAT Examples ........................................................................................................... 9-16
9.5.1 Internet Access Only ........................................................................................................ 9-16
9.5.2
Example 2: Internet Access with an Inside Server ........................................................... 9-17
9.5.3 Example 3: Multiple Public IP Addresses With Inside Servers........................................ 9-18
9.5.4 Example 4: NAT Unfriendly Application Programs ........................................................ 9-22
FIREWALL AND CONTENT FILTERS ....................................................................................................III
Chapter 10 Firewalls.............................................................................................................................. 10-1
10.1 What Is a Firewall?............................................................................................................... 10-1
10.2 Types of Firewalls ................................................................................................................ 10-1
10.2.1 Packet Filtering Firewalls................................................................................................. 10-1
10.2.2 Application-level Firewalls .............................................................................................. 10-1
10.2.3 Stateful
Inspection Firewalls ............................................................................................ 10-2
10.3 Introduction to ZyXEL’s Firewall........................................................................................ 10-2
10.4 Denial of Service .................................................................................................................. 10-3
10.4.1 Basics ............................................................................................................................... 10-3
10.4.2 Types of DoS Attacks....................................................................................................... 10-4
10.5 Stateful Inspection ................................................................................................................ 10-7
10.5.1 Stateful Inspection Process............................................................................................... 10-8
10.5.2 Stateful Inspection and the ZyWALL............................................................................... 10-9
10.5.3 TCP Security .................................................................................................................. 10-10