On Fri, 10 Jan 1997, Ken Hornstein wrote:

> >Can anyone point me to a good documentation of the Berkeley Packet
> >Filters? Reading other people's source is not a strength of mine,
> >that's why I am looking for a book, web page or any other document
> >that describes how to program them in detail.
> 
> The two best sources of information about them I've found are the bpf man
> page, and the Usenix white paper (should be able to find it on ftp.ee.lbl.gov).

It is at:

	ftp://ftp.ee.lbl.gov/papers/bpf-usenix93.ps.Z

to be exact.  From what I recall, it doesn't go deeply into the API but
presents a very useful conceptual overview that lets you understand how
things are done.