Before clicking that download button, it is critical to understand what YAF actually does. YAF is an open-source tool developed by the CERT Division of the Software Engineering Institute at Carnegie Mellon University. Contrary to what the name "extractor" might imply, YAF does not "extract" files like a ZIP utility. Instead, it extracts flow metadata from network traffic.
https://tools.netsa.cert.org/yaf/
For , YAF is available via the CERT NetSA repository: yaf extractor download