In some email I received from Perry E. Metzger, sie wrote:
> 
> Darren Reed <darrenr@reed.wattle.id.au> writes:
> > > I don't know about divert sockets, but I see two alternatives:
> > > 1) the standard bpf interface  as used e.g. by IDS systems like
> > >    snort (it's in pkgsrc)
> > 
> > divert isn't as lossy as bpf is.
> 
> Er, at some point any such mechanism will fill its queues. It is just
> a question of policy. If you need more buffering because of transient
> scheduling issues, you can increase the size of the buffering bpf has
> available. If you can't process the packets as fast as they appear, no
> amount of buffering will help.
> 
> Remember, btw, the network itself is lossy.
> 
> To my mind, bpf is sufficient. Hell, NFR uses it and that's the best IDS
> I know.

NFR does not use the same version of BPF as we do.  They optimized it.
Can ours be optimized ?  Yes but tcpdump.org doesn't seem too interested.

Darren