Abstract
Although computer intrusions have exsisted from the moment of the Internet's
birth, until recently system administrators either did not consider them to be
a serious problem or were totally ignoring them. Unfortunately, hiding their
heads in the sand did not make intrusions disapper; rather, it gave the
intruders time to create more and more sophisticated attack tools, making the
countermeasures necessary to block the attacks a very high tech, time
and monetary consuming activity. This paper is an attempt to summarize the
techniques used to detect and successfully defeat attacks launched by
the intruders equipped with the modern intrusion kits in high availablility
environments such as the communication carriers.
