Custom Application Mappings

The application option specifies the Layer 7 application that maps to the Layer 4 application that you reference in a policy. A predefined application already has a mapping to a Layer 7 application. However, for custom applications, you must link the application to an application explicitly, especially if you want the policy to apply an Application Layer Gateway (ALG) or deep inspection to the custom application.

Note: Junos OS supports ALGs for numerous applications, including DNS, FTP, H.323, HTTP, RSH, SIP, Telnet, and TFTP.

Applying an ALG to a custom application involves the following two steps:

• Define a custom application with a name, timeout value, transport protocol, and source and destination ports.
• When configuring a policy, reference that application and the application type for the ALG that you want to apply.

Related Topics

• Junos OS Feature Support Reference for SRX Series and J Series Devices
• Security Policy Applications Overview
• Understanding Custom Policy Applications
• Understanding Policy Application Timeout Configuration and Lookup
• Understanding Policy Application Timeouts Contingencies
• Example: Adding and Modifying Custom Policy Applications