This is just a quick one. I recently needed to filter out a couple packet captures of unneeded frames/packets for some training material. I had unfortunately captured a crap ton of data though and really didn’t want to post the whole 20M pcap file. I ran across the wireshark function called “editcap”. There is a lot that you can do with editcap as you can see in the following link:
Editing trace files with Editcap
However all I needed to do was remove the frames before and after the area of interest. To do this on a macbook:
editcap -r {source file} {destination file} {packets/frames you want to keep}
e.g.
editcap -r wirelesseapol.pcap wirelesseapolfiltered.pcap 790-900
This will take the wirelesseapol.pcap, remove frames 1-789 and 901 – end, leaving me 790-900 in a new packet captures called wirelesseapolfiltered.pcap.
You can also do this in wireshark using the export specified packets feature. However CLI can be fun.