Hypertext Transfer Protocol (HTTP)

author: Nathan Acks
date: 2022-03-13

A Minimal HTTP Request

GET / HTTP/1.1
host: something

(Note the blank line at the end.)

Useful HTTP Headers

• Server - Web server information (Apache, NGINX, etc.); useful for recon.
• True-Client-IP - Override the client IP address (direct connections to servers).
• X-Forwarded-For - Override the client IP address (connections forwarded through proxies).
• X-Powered-By - Added by some application engines to advertise themselves; useful for recon.
• Content-Type - Specifies the body content; normally only set by the client for POST/PATCH requests (for example, form data uses application/x-www-form-urlencoded.
• Content-Length - The length of the body in bytes (which is just characters for ASCII) for POST requests.

There are other headers (for example, Cookie), and arbitrary additional X-prefixed (non-standard) headers can also be added.

• Content-Length (MDN)