In the following passage some of the words have been deleted. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

Network security (1) ______ securing a network and protecting the user’s information about (2) ______ is connected through that network. Over the network (3) ______ steal, the packets of data through sniffing and spoofing (4) ______, man in the middle attack, war driving, etc, and misuse the data for their (5) ______.