# HyperText Transfer Protocol (HTTP)

<figure><img src="/files/AoYFN9nXAxLHW5yfW6ga" alt=""><figcaption></figcaption></figure>

## HTTP Flow

<figure><img src="/files/QyY3VDuruebekaL4gl07" alt=""><figcaption></figcaption></figure>

> Note: Our browsers usually first look up records in the local '`/etc/hosts`' file, and if the requested domain does not exist within it, then they would contact other DNS servers. We can use the '`/etc/hosts`' to manually add records to for DNS resolution, by adding the IP followed by the domain name.

## cURL

### Basic cURL

In this module, we will be sending web requests through two of the most important tools for any web penetration tester, a Web Browser, like Chrome or Firefox, and the `cURL` command line tool.

| `curl -h`                                                                                                        | cURL help menu                                       |
| ---------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------- |
| `curl inlanefreight.com`                                                                                         | Basic GET request                                    |
| `curl -s -O inlanefreight.com/index.html`                                                                        | Download file                                        |
| `curl -k https://inlanefreight.com`                                                                              | Skip HTTPS (SSL) certificate validation              |
| `curl inlanefreight.com -v`                                                                                      | Print full HTTP request/response details             |
| `curl -I https://www.inlanefreight.com`                                                                          | Send HEAD request (only prints response headers)     |
| `curl -i https://www.inlanefreight.com`                                                                          | Print response headers and response body             |
| `curl https://www.inlanefreight.com -A 'Mozilla/5.0'`                                                            | Set User-Agent header                                |
| `curl -u admin:admin http://<SERVER_IP>:<PORT>/`                                                                 | Set HTTP basic authorization credentials             |
| `curl http://admin:admin@<SERVER_IP>:<PORT>/`                                                                    | Pass HTTP basic authorization credentials in the URL |
| `curl -H 'Authorization: Basic YWRtaW46YWRtaW4=' http://<SERVER_IP>:<PORT>/`                                     | Set request header                                   |
| `curl 'http://<SERVER_IP>:<PORT>/search.php?search=le'`                                                          | Pass GET parameters                                  |
| `curl -X POST -d 'username=admin&password=admin' http://<SERVER_IP>:<PORT>/`                                     | Send POST request with POST data                     |
| `curl -b 'PHPSESSID=c1nsa6op7vtk7kdis7bcnbadf1' http://<SERVER_IP>:<PORT>/`                                      | Set request cookies                                  |
| `curl -X POST -d '{"search":"london"}' -H 'Content-Type: application/json' http://<SERVER_IP>:<PORT>/search.php` | Send POST request with JSON data                     |

### APIs

| `curl http://<SERVER_IP>:<PORT>/api.php/city/london`                                                                                                    | Read entry            |
| ------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------- |
| `curl -s http://<SERVER_IP>:<PORT>/api.php/city/ \| jq`                                                                                                 | Read all entries      |
| `curl -X POST http://<SERVER_IP>:<PORT>/api.php/city/ -d '{"city_name":"HTB_City", "country_name":"HTB"}' -H 'Content-Type: application/json'`          | Create (add) entry    |
| `curl -X PUT http://<SERVER_IP>:<PORT>/api.php/city/london -d '{"city_name":"New_HTB_City", "country_name":"HTB"}' -H 'Content-Type: application/json'` | Update (modify) entry |
| `curl -X DELETE http://<SERVER_IP>:<PORT>/api.php/city/New_HTB_City`                                                                                    | Delete entry          |


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://eldeim.gitbook.io/brain_fuck/notes/certifications/eastereggs/htb-cbbh/web-requests-fundamentals/http-fundamentals/hypertext-transfer-protocol-http.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.