Layer 7 of the OSI model is the application layer. This is the top layer of the OSI model. The application layer interfaces directly to applications and application processes. Applications play a critical role in network security; they can be designed so they are completely insecure, somewhat secure, or very resistant to attacks.

Many applications, such as file transfer protocol (FTP), Telnet, Simple Mail Transfer Protocol (SMTP) and Domain Name System (DNS), have been around so long that the threats they face today were never envisioned when they were originally designed. As two of the 13