Abstract:

The TCP/IP network stack offers different communication services through defined standard transport and network layer protocols. It represents a networking subsystem that is currently used by most of the application layer protocols - for example, DNS (Domain Name System), FTP (File Transfer Protocol), HTTP (Hypertext Transfer Protocol), different e-mail protocols, and many others. All application protocols rely on transport layer protocols (TCP or UDP), but in their standard form, they completely lack any data security mechanisms. That is why nowadays networks include "security layer" protocols such as TLS (Transport Layer Security).

When introducing application protocols to our undergraduate STEM students, we provide clear lab examples in which basic protocol facts can be checked by simply recording and analyzing network traffic at the host. This paper gives an introduction to a few often-used application layer protocols and their relation to the TCP/IP network stack. It includes the description of our standard networking lab - using the well-known network analyzer, Wireshark, students have to notice and try to explain some specific events and protocol behaviors. Two application protocol-related labs are described - DNS and HTTP labs. As part of the HTTP lab, the basics of securing transferred data are depicted, explained, and hopefully, confirmed by students.

Generally, the goal of the paper is to provide an explanatory example that can help STEM students understand the basics of everyday used application protocols.

Keywords:

TCP/IP, application protocol, Wireshark, STEM, networking, HTTP, DNS.