I'm guessing Berkeley Packet Filter: https://en.wikipedia.org/wiki/Berkeley_Packet_Filter

This is why National Aeronautics & Space Administration (NASA) guidance is the following:

> Acronyms often confuse readers. Avoid them whenever possible. If an acronym is necessary for future reference, spell the full word and follow with the acronym in parentheses on the first reference. For example, The General Services Administration (GSA).

https://nasa.github.io/content-guide/abbreviations-and-acron...

There is also this longer memo on the NASA Technical Reports Server: https://ntrs.nasa.gov/citations/19950025292

'berkeley packet filters', these days 'extended berkeley packet filters', are little program snippets you can inject into the linux kernel from userland programs to run logic on hooks on various events without the need to switch back to userspace.

It's a low level networking interface https://en.wikipedia.org/wiki/Berkeley_Packet_Filter

BPF == 'Berkeley Packet Filter'

Here you go: https://github.com/pratyushanand/learn-bpf