Hypertext Transfer Protocol

HTTP (Hypertext Transfer Protocol) is an application-level protocol used to access World Wide Web resources. The communication consists of a client requests from a server where the server processes the request and sends back a response. HTTP uses port 80 by default but is configurable.

URL Structure

A URL (Uniform Resource Locator) specifies the resource location and how to access it.

1. Scheme: Identifies the protocol (http://, https://).
2. User Info: Optional credentials (admin:password@).
3. Host: Specifies the hostname or IP (inlanefreight.com).
4. Port: Defaults to 80 for http and 443 for https (:80).
5. Path: The file or folder being accessed (/dashboard.php).
6. Query String: Parameters and values (?login=true).
7. Fragments: Client-side sections within the resource (#status).

HTTP Request Flow

1. DNS Resolution:
   • Resolves the domain (e.g., inlanefreight.com) to an IP address.
   • Checks /etc/hosts locally first, then queries DNS servers.
2. GET Request:
   • Browser sends a request to the server’s root / path.
   • Server responds with an index file (e.g., index.html) and a status code (e.g., 200 OK).

Using cURL

cURL is a command-line tool for sending HTTP requests, often used in automation and web penetration testing.

curl <url> <- raw HTML code
curl -O inlanefreight.com/index.html <- saves the file
curl -s -O inlanefreight.com/index.html <- supresses status info

Flag	Description
-d, --data	HTTP POST data
-i, --include	Include response headers in the output
-o, --output <file>	Write to file instead of standard output
-O, --remote-name	Save output with the remote file’s name
-s, --silent	Enable silent mode
-u, --user	Use username and password for authentication (<user>:<password>)
-A, --user-agent	Specify a custom User-Agent
-v, --verbose	Enable verbose mode for detailed operation logs