Description

What is the maximum packet size and file size for packet captures on a Juniper SRX firewall?

Solution

In Juniper SRX packet capture configuration, the maximum-capture-size parameter defines the maximum size of each individual packet to be captured, which can range from 68 bytes to 1520 bytes. Additionally, the file filename <name> size <size> command allows you to specify the maximum size of a single PCAP file, with a configurable range from 1024 bytes (1 KB) up to 104857600 bytes (~100 MB). 

 

root# set forwarding-options packet-capture maximum-capture-size ?

Possible completions:

 <maximum-capture-size> Maximum packet size to capture (68..1520 bytes)

[edit]

root# set forwarding-options packet-capture file filename test size ?

Possible completions:

 <size>        Maximum file size (1024..104857600)

[edit]

root# set forwarding-options packet-capture file filename test size ""

 

This helps in managing disk space and organizing capture files effectively during troubleshooting or traffic analysis.

Modification History

2025-07-30 : Article Created