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[SRX] How to perform a packet capture for traffic destined to or sourced from the routing-engine of a SRX



Article ID: KB35651 KB Last Updated: 31 Mar 2020Version: 1.0
This article explains a way for taking a packet-capture (tcpdump) on a SRX firewall for traffic destined to or sourced from the routing-engine of the device. Note that with this method you cannot capture transit traffic, only self traffic.

For packet-captures of transit traffic see the following articles:

The monitor traffic tool can be leveraged for this packet-capture purposes by using the write-file statement. An example of the command is the following:

root@srx> monitor traffic interface ge-0/0/0.0 write-file CAPTURE.pcap <-- write-file is a hidden command so it will not auto-complete and must be typed out

With the above command all traffic to or from the Routing Engine that is forwarded over interface ge-0/0/0.0 will be saved to a file named CAPTURE with a file extension type of pcap. After this, you can download the file from the SRX and open it in a traffic analyzer tool such as Wireshark.

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