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In the 1980s, the **Line Printer Daemon (LPD) protocol** was developed in Berkeley Unix, which later became formalized through RFC1179. This protocol operates over port 515/tcp, allowing interactions through the `lpr` command. The essence of printing via LPD involves sending a **control file** (to specify job details and user) along with a **data file** (which holds the print information). While the control file allows the selection of **various file formats** for the data file, the handling of these files is determined by the specific LPD implementation. A widely recognized implementation for Unix-like systems is **LPRng**. Notably, the LPD protocol can be exploited to execute **malicious PostScript** or **PJL print jobs**.
[**PRET**](https://github.com/RUB-NDS/PRET) introduces two essential tools, `lpdprint` and `lpdtest`, offering a straightforward method to interact with LPD-compatible printers. These tools enable a range of actions from printing data to manipulating files on the printer, such as downloading, uploading, or deleting:
For individuals interested in further exploring the realm of **printer hacking**, a comprehensive resource can be found here: [**Hacking Printers**](http://hacking-printers.net/wiki/index.php/Main_Page).
Learn & practice AWS Hacking:<imgsrc="/.gitbook/assets/arte.png"alt=""data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<imgsrc="/.gitbook/assets/arte.png"alt=""data-size="line">\
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.