ZyXEL Communications ZyXEL ZyWALL 35 - Manual (Page 12)

ZyWALL 35 User’s Guide
10
7.11 Configuring Dial Backup .................................................................................158
7.12 Advanced Modem Setup ................................................................................162
7.12.1 AT Command Strings ............................................................................162
7.12.2 DTR Signal ...........................................................................................162
7.12.3 Response Strings ..................................................................................162
7.13 Configuring Advanced Modem Setup ............................................................162
Chapter 8
DMZ Screens ........................................................................................................ 165
8.1 DMZ Overview .................................................................................................165
8.2 Configuring DMZ ..............................................................................................165
8.3 Configuring IP Alias ..........................................................................................167
8.4 DMZ Public IP Address Example .....................................................................169
8.5 DMZ Private and Public IP Address Example ..................................................169
8.6 Configuring Port Roles .....................................................................................170
Chapter 9
Firewalls................................................................................................................ 173
9.1 Firewall Overview .............................................................................................173
9.2 Types of Firewalls ............................................................................................173
9.2.1 Packet Filtering Firewalls ........................................................................173
9.2.2 Application-level Firewalls ......................................................................173
9.2.3 Stateful Inspection Firewalls ...................................................................174
9.3 Introduction to ZyXEL’s Firewall .......................................................................174
9.4 Denial of Service ..............................................................................................175
9.4.1 Basics .....................................................................................................175
9.4.2 Types of DoS Attacks .............................................................................176
9.4.2.1 ICMP Vulnerability ........................................................................178
9.4.2.2 Illegal Commands (NetBIOS and SMTP) ......................................178
9.4.2.3 Traceroute .....................................................................................179
9.5 Stateful Inspection ............................................................................................179
9.5.1 Stateful Inspection Process ....................................................................180
9.5.2 Stateful Inspection and the ZyWALL .......................................................181
9.5.3 TCP Security ...........................................................................................181
9.5.4 UDP/ICMP Security ................................................................................182
9.5.5 Upper Layer Protocols ............................................................................182
9.6 Guidelines For Enhancing Security With Your Firewall ....................................183
9.7 Packet Filtering Vs Firewall ..............................................................................183
9.7.1 Packet Filtering: ......................................................................................183
9.7.1.1 When To Use Filtering ...................................................................183
9.7.2 Firewall ...................................................................................................184
9.7.2.1 When To Use The Firewall ............................................................184