ZyXEL Communications ZyWall 35 User Manual page 13

9.5.1 Stateful Inspection Process ....................................................................170
9.5.2 Stateful Inspection and the ZyWALL .......................................................171
9.5.3 TCP Security ...........................................................................................171
9.5.4 UDP/ICMP Security ................................................................................172
9.5.5 Upper Layer Protocols ............................................................................172
9.6 Guidelines For Enhancing Security With Your Firewall ....................................173
9.7 Packet Filtering Vs Firewall ..............................................................................173
9.7.1 Packet Filtering: ......................................................................................173
9.7.1.1 When To Use Filtering ...................................................................173
9.7.2 Firewall ...................................................................................................174
9.7.2.1 When To Use The Firewall ............................................................174
Chapter 10
Firewall Screens................................................................................................... 175
10.1 Access Methods .............................................................................................175
10.2 Firewall Policies Overview .............................................................................175
10.3 Rule Logic Overview ......................................................................................176
10.3.1 Rule Checklist .......................................................................................176
10.3.2 Security Ramifications ..........................................................................177
10.3.3 Key Fields For Configuring Rules .........................................................177
10.3.3.1 Action ..........................................................................................177
10.3.3.2 Service ........................................................................................177
10.3.3.3 Source Address ...........................................................................177
10.3.3.4 Destination Address ....................................................................177
10.4 Connection Direction Examples .....................................................................177
10.4.1 LAN To WAN Rules ..............................................................................178
10.4.2 WAN To LAN Rules ..............................................................................178
10.5 Alerts ..............................................................................................................179
10.6 Configuring Firewall .......................................................................................179
10.6.1 Rule Summary ......................................................................................182
10.6.2 Configuring Firewall Rules ....................................................................183
10.6.3 Configuring Custom Services ...............................................................186
10.7 Example Firewall Rule ...................................................................................186
10.8 Predefined Services .......................................................................................190
10.9 Anti-Probing ...................................................................................................192
10.10 DoS Thresholds ...........................................................................................193
10.10.1 Threshold Values ................................................................................194
10.10.2 Half-Open Sessions ............................................................................194
10.10.2.1 TCP Maximum Incomplete and Blocking Time .........................194
Chapter 11
Content Filtering Screens ................................................................................... 197
11.1 Content Filtering Overview .............................................................................197
ZyWALL 35 User's Guide
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