The Application Layer of the TCP/IP stack consists of the Application, Presentation, and Session Layers of the OSI reference model. As we learned before, whenever a computer wants to send traffic (datagrams) to the network, the creation of the Protocol Data Units (PDUs) begins at the top of the TCP/IP stack, the Application Layer:
The following are some of the application layer protocols which we should pay close attention to on our network:
- File Transfer Protocol (FTP)
- Telnet
- Secure Shell (SSH)
- Simple Mail Transfer Protocol (SMTP)
- Domain Name System (DNS)
- Dynamic Host Configuration Protocol (DHCP)
- Hypertext Transfer Protocol (HTTP)
Each of these protocols was designed to provide the function it was built to do, and with a lesser focus on security. Malicious users and hackers are able to compromise both the application that utilizes...