Use the Packet Capture page when you need to quickly capture and analyze router control traffic on a device. The Packet Capture page allows you to capture traffic destined for or originating from the Routing Engine. You can use the packet capture task to compose expressions with various matching criteria to specify the packets that you want to capture. You can either choose to decode and view the captured packets in the J-Web interface as they are captured, or save the captured packets to a file and analyze them offline with packet analyzers such as Ethereal. The packet capture task does not capture transient traffic.
Alternatively, you can use the CLI monitor traffic command at the J-Web CLI terminal to capture and display packets matching a specific criteria. For more information, see Using the CLI Terminal. For more information about the monitor traffic command, see the Junos OS System Basics and Services Command Reference.
To capture transient traffic and entire IPv4 data packets for offline analysis, you must configure packet capture with the J-Web or CLI configuration editor. For details, see the JUNOS Enhanced Services Administration Guide.