Technology Insights

How to Merge Multiple WLAN (IEEE 802.11) Captures into One File

I recently had a customer upload a WPA capture to our tools.question-defense.com server which failed immediately. This can happen from time to time and is for a variety of reasons Sometimes if captures does not contain all 4 eapol packets they will fail , and sometimes if a capture has lots of other wifi garbage in the .cap file it can confuse the cracking program. This last time was a new situation. After the fail I analyzed the cap file and determined that the essid was not present in the capture. This is absolutely crucial for the decrypting process. In this short article I will show how I determined the essid was not present and what I did about it.