In a communication system, authentication verifies that messages actually come from their stated source, like the signature on a paper letter. It works by assigning a unique key, called a ticket, to each user who logs on. The ticket is then embedded in messages to identify the sender of the message.
Some sites attempt to use firewalls to solve their network security problems.
Most of the damaging incidents of computer crime are performed by insiders. In Greek mythology, Kerberos was the three-headed dog that guarded the entrance to Hades. Some of you who know Greek mythology may remember that the dog who guarded the entrance was called Cerberus, not Kerberos. Cerberus is the Latin spelling of the Greek Kerberos. In Latin, the letter 'c' is always hard.