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.
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Note: JUNOS software 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: