> All of the products mentioned in the previous messages provide passive
> monitoring only. Are there any PC-based products that in addition to
> monitoring packet traffic can also intervene with the flow of packets,
> i.e., block packets from reaching certain application or leaving the
> PC, based on user-defined rules?
> It seems that a tool like this will provide a much better control over
> network traffic.
Sure will, but it's called a packet filter, not a sniffer. I think a
generally accepted characteristic of a sniffer is that it captures
packets not intended for it off the wire, as opposed to packets flowing
through it, a' la packet filtering routers.
And at least the Novell LANalyzer product goes beyond passivity: it will
do load generation by spewing packets and will also replay captured packet
streams back onto the wire. Or at least, my version does, but since it
doesn't exist, according to Novell, I may be a figment of my own
W.C. Epperson "I have great faith in fools.
Senior SE Self-confidence, my friends call it."
Information Security Officer --Edgar Allan Poe--
Virginia Dept. of Education