Explanation:
The intruder determines the nature of the flow of traffic (traffic analysis) between defined hosts and is able to guess the type of communication taking place. Message modification involves the capturing of a message and making unauthorized changes or deletions, changing the sequence or delaying transmission of captured messages. Masquerading is an active attack in which the intruder presents an identity other than the original identity. Denial of service occurs when a computer connected to the internet is flooded with data and/or requests that must be processed.