
5
Table of Contents
Using Access Rules . . . . . . . . . . . . . . . . . . . . 93
Allowing System Communications . . . . . . . . . 93
Configuring Default Settings for Several Rules 94
Using Continue Rules to Set Logging
Options . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Using Continue Rules to set the
Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Using Aliases in Access Rules. . . . . . . . . . . . 95
Examples of Access Rules. . . . . . . . . . . . . . . . 96
Example of Rule Order . . . . . . . . . . . . . . . . . 96
Example of Continue Rules . . . . . . . . . . . . . . 98
CHAPTER 10
Inspection Rules . . . . . . . . . . . . . . . . . . . . . . . 99
Overview to Inspection Rules. . . . . . . . . . . . . . 100
Configuration of Inspection Rules. . . . . . . . . . . 101
Considerations for Designing Inspection Rules 102
Exception Rule Cells . . . . . . . . . . . . . . . . . . . 103
Default Elements . . . . . . . . . . . . . . . . . . . . . 104
Configuration Workflow . . . . . . . . . . . . . . . . . 104
Task 1: Activate Deep Inspection in
Access Rules . . . . . . . . . . . . . . . . . . . . . . . 105
Task 2: Activate the Relevant Inspection
Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Task 3: Define the Exceptions . . . . . . . . . . . 105
Task 4: Eliminate False Positives. . . . . . . . . 106
Task 5: Add Custom Inspection Checks . . . . 106
Using Inspection Rules . . . . . . . . . . . . . . . . . . 106
Setting Default Options for Several Inspection
Rules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Example of Inspection Rules . . . . . . . . . . . . . . 107
Eliminating a False Positive . . . . . . . . . . . . . . 107
CHAPTER 11
Network Address Translation (NAT) Rules . . . . 109
Overview to NAT . . . . . . . . . . . . . . . . . . . . . . . 110
Static Source Translation . . . . . . . . . . . . . . . 110
Dynamic Source Translation . . . . . . . . . . . . . 111
Static Destination Translation . . . . . . . . . . . . 112
Destination Port Translation . . . . . . . . . . . . . 112
Configuration of NAT . . . . . . . . . . . . . . . . . . . . 113
Considerations for Designing NAT Rules . . . . . 115
Default Elements . . . . . . . . . . . . . . . . . . . . . 115
Configuration Workflow . . . . . . . . . . . . . . . . . 115
Task 1: Define Source, Destination, and
Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Task 2: Define Address Translation . . . . . . . 115
Task 3: Define the Firewall(s) that Apply
the Rule. . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Task 4: Check Other Configurations. . . . . . . 116
Using NAT and NAT Rules . . . . . . . . . . . . . . . . 116
NAT and System Communications . . . . . . . . . 116
Example of a Situation Where a
Contact Address is Needed . . . . . . . . . . . . 117
Contact Addresses and Locations . . . . . . . . 118
Outbound Load Balancing NAT . . . . . . . . . . . 118
Proxy ARP and NAT. . . . . . . . . . . . . . . . . . . . 119
Protocols and NAT . . . . . . . . . . . . . . . . . . . . 119
Examples of NAT . . . . . . . . . . . . . . . . . . . . . . 119
Dynamic Source Address Translation . . . . . . . 119
Static Address Translation . . . . . . . . . . . . . . 120
NAT with Hosts in the Same Network. . . . . . . 120
CHAPTER 12
Protocol Agents . . . . . . . . . . . . . . . . . . . . . . . 123
Overview to Protocol Agents . . . . . . . . . . . . . . 124
Connection Handling . . . . . . . . . . . . . . . . . . 124
Protocol Validation . . . . . . . . . . . . . . . . . . . . 124
NAT in Application Data . . . . . . . . . . . . . . . . 125
Configuration of Protocol Agents . . . . . . . . . . . 125
Configuration Workflow . . . . . . . . . . . . . . . . . 125
Task 1: Create a Custom Service with
a Protocol Agent . . . . . . . . . . . . . . . . . . . . 125
Task 2: Set Parameters for the Protocol
Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Task 3: Insert the Service in Access
Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Using Protocol Agents . . . . . . . . . . . . . . . . . . 126
FTP Agent . . . . . . . . . . . . . . . . . . . . . . . . . . 126
H.323 Agent . . . . . . . . . . . . . . . . . . . . . . . . 127
HTTP Agents . . . . . . . . . . . . . . . . . . . . . . . . 127
HTTPS Agent . . . . . . . . . . . . . . . . . . . . . . . . 127
ICMP Agent . . . . . . . . . . . . . . . . . . . . . . . . . 128
MSRPC Agent . . . . . . . . . . . . . . . . . . . . . . . 128
NetBIOS Agent. . . . . . . . . . . . . . . . . . . . . . . 128
Oracle Agent . . . . . . . . . . . . . . . . . . . . . . . . 128
Remote Shell (RSH) Agent . . . . . . . . . . . . . . 128
Services in Firewall Agent . . . . . . . . . . . . . . . 129
SIP Agent . . . . . . . . . . . . . . . . . . . . . . . . . . 129
SMTP Agent. . . . . . . . . . . . . . . . . . . . . . . . . 129
SSH Agent. . . . . . . . . . . . . . . . . . . . . . . . . . 129
SunRPC Agent . . . . . . . . . . . . . . . . . . . . . . . 129
TCP Proxy Agent. . . . . . . . . . . . . . . . . . . . . . 130
TFTP Agent . . . . . . . . . . . . . . . . . . . . . . . . . 130
Examples of Protocol Agent Use . . . . . . . . . . . 130
Preventing Active Mode FTP . . . . . . . . . . . . . 130
Logging URLs Accessed by Internal Users . . . 131