ZyXEL Communications ZyWALL 5 User Manual page 12

ZyWALL 5 User's Guide
7.8 Advanced Modem Setup ..................................................................................139
7.9 Configuring Advanced Modem Setup ..............................................................139
Chapter 8
DMZ Screens ........................................................................................................ 143
8.1 DMZ Overview .................................................................................................143
8.2 Configuring DMZ ..............................................................................................143
8.3 Configuring IP Alias ..........................................................................................145
8.4 DMZ Public IP Address Example .....................................................................147
8.5 DMZ Private and Public IP Address Example ..................................................148
8.6 Configuring Port Roles .....................................................................................148
Chapter 9
Firewalls................................................................................................................ 151
9.1 Firewall Overview .............................................................................................151
9.2 Types of Firewalls ............................................................................................151
9.3 Introduction to ZyXEL's Firewall .......................................................................152
9.4 Denial of Service ..............................................................................................153
9.5 Stateful Inspection ............................................................................................157
9.6 Guidelines For Enhancing Security With Your Firewall ....................................161
9.7 Packet Filtering Vs Firewall ..............................................................................161
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7.8.1 AT Command Strings ..............................................................................139
7.8.2 DTR Signal .............................................................................................139
7.8.3 Response Strings ....................................................................................139
9.2.1 Packet Filtering Firewalls ........................................................................151
9.2.2 Application-level Firewalls ......................................................................151
9.2.3 Stateful Inspection Firewalls ...................................................................152
9.4.1 Basics .....................................................................................................153
9.4.2 Types of DoS Attacks .............................................................................154
9.4.2.1 ICMP Vulnerability ........................................................................156
9.4.2.2 Illegal Commands (NetBIOS and SMTP) ......................................156
9.4.2.3 Traceroute .....................................................................................157
9.5.1 Stateful Inspection Process ....................................................................158
9.5.2 Stateful Inspection and the ZyWALL .......................................................159
9.5.3 TCP Security ...........................................................................................159
9.5.4 UDP/ICMP Security ................................................................................160
9.5.5 Upper Layer Protocols ............................................................................160
9.7.1 Packet Filtering: ......................................................................................161
9.7.1.1 When To Use Filtering ...................................................................161
9.7.2 Firewall ...................................................................................................162
9.7.2.1 When To Use The Firewall ............................................................162