ABSTRACT
This chapter considers practical matter of network security. It begins by considering fundamental concept: safeguards are needed to make Internet communication and transactions secure. The chapter examines two important technologies that help users keep communication confidential and help keep computers safe from unwanted packets. The victim is given a choice of paying to remove the ransomware or risking the ransomware erasing all the user's data. It turned out that the criminals did not need to use the Internet to gain access because they bribed an employee who allowed them to enter after hours and access the database. Many of the networks that constitute the Internet are “shared,” which means that multiple computers attach. Since ancient times, people have used secret codes to keep messages from being read by outsiders. The codes used with modern digital systems differ from the codes used in ancient times because code breaking in the modern world is completely different than code breaking in earlier times.
