> For the complete documentation index, see [llms.txt](https://106-sam.gitbook.io/ejptv2-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://106-sam.gitbook.io/ejptv2-notes/system-host-based-attacks/linux-vulnerabilities.md).

# Linux Vulnerabilities

### Frequently Exploited Linux Service

* Linux is a free and open source operating system that is comprised of the Linux kernel, which was developed by Linus Torvalds, and the GNU toolkit, which is a collection of software and utilities that was started and developed by Richard Stallman.
* This combination of open source source software is what makes up the Linux OS as a whole, and it is commonly referred to as GNU/Linux.
* Linux has various use cases, however, it is typically deployed as a server operating system. For this reason, there are specific services and protocols that will typically be found running on a Linux server. 
* These services provide an attacker with an access vector that they can utilize to gain access to a target host.
* Having a good understanding of what these services are, how they work and their potential vulnerabilities is a vitally important skill to have as a penetration tester.

| Protocol/Service             | Ports            | Purpose                                                                                                                                                                         |
| ---------------------------- | ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Apache Web Server            | TCP ports 80/443 | Free and open source cross-platform web server released under the Apache License 2.0. Apache accounts for over 80% of web servers globally.                                     |
| SSH (Secure Shell)           | TCP ports 22     | SSH is a cryptographic remote access protocol that is used to remotely access and control systems over an unsecured network. SSH was developed as a secure successor to telnet. |
| FTP (File Transfer Protocol) | TCP port 21      | FTP is a protocol that uses TCP port 21 and is used to facilitate file sharing between a server and client/clients and vice versa.                                              |
| SAMBA                        | TCP port 445     | Samba is the Linux implementation of SMB, and allows Windows systems to access Linux shares and devices.                                                                        |