This is a big problem. A Real Big problem. In today's lecture, we concentrate on this problem. Security of information in transit across the network. This is covered in the next lecture.
Solution is usually in some form of encryption , see next lectures.
Such access can be obtained by a wide variety of means. This is probably the most important type of attack. Most interest in security issues is in connecting to the Internet in a secure way. Even reverse lookups can be compromised by manipulation of DNS tables or by IP Spoofing, where a remote host generates IP packets that look as though they came from some other system. An issue here is whether the vendor provides access to source code for scrutiny.