Learn › The Network Stack

The Application Layer

DNS, TLS, HTTP. The protocols that sit on top of TCP. Every connection starts with a name lookup and ends with data. See all of it from the terminal.

Labs in this module

• DNS - Every network connection starts with a name lookup. dig lets you make DNS queries and see the full response. This is the bridge between name
• TLS - The handshake inside the handshake. Certificate chain, cipher negotiation, all visible in the terminal.
• HTTP - Request line, headers, status code, body. The protocol you use a thousand times a day, seen raw.
• The Full Stack - One curl request. Every layer visible from Linux. Frame, IP, TCP, TLS, HTTP, all in one capture.