Here is something for your weekend list of things to ponder...
I heard from a potential customer (small ISP) yesterday that tried a
Challenge/Response system for 4 hours.
Here is what happened (as best as I can explain it).
He implements the Challenge/Response system.
A few of his users send
Users of some remote system using Challenge/Response send his users
messages
and his system generates Challenge messages. The remote server receives
the
Challenge messages and sends new Challenge messages back to his server.
His
server sends back bounce messages because his Challenge messages
