What Service Do We Use To Form Our VPN Connection Into Htb Labs?

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Introduction to VPNs

A Virtual Private Network (VPN) encrypts a device's internet connection and routes it through a server in a chosen location. This protects privacy and bypasses internet censorship. In the context of Hack The Box (HTB), VPNs establish a secure connection between a user's device and HTB's internal network, allowing access to vulnerable machines as if physically connected.

The Service Used: OpenVPN

To form a VPN connection into HTB labs, OpenVPN is used. OpenVPN is an open-source software application creating a secure point-to-point connection over the internet. It is widely used for remote access to corporate networks and is the preferred method for accessing HTB's internal lab networks.

Why OpenVPN?

OpenVPN is chosen for several reasons:

1. Security: Provides robust encryption, ensuring all data transmitted over the VPN is secure.
2. Flexibility: Supports both TCP and UDP protocols, allowing users to choose the best protocol based on network conditions.
3. Ease of Use: Configuration files are straightforward to set up, making it accessible to users with varying levels of technical expertise.
4. Cross-Platform Compatibility: Runs on multiple operating systems, including Windows, macOS, and Linux, making it versatile for different environments.

Configuring OpenVPN

To configure OpenVPN for accessing HTB labs, follow these steps:

1. Account Requirements: A Hack The Box account is needed to access VPN configuration files. These files, called VPN packs or VPN files, auto-configure the OpenVPN client.

2. Download VPN File: Select the content type (e.g., Machines, Starting Point, Endgame) and choose the preferred connection method (VPN file or Pwnbox option). Download the VPN configuration file, typically found in the Downloads folder of a Linux distro by default.

3. OpenVPN Initialization: Open a terminal and navigate to the location of the downloaded VPN configuration file. Initialize the OpenVPN connection using the following command:
   bash
   openvpn –config .ovpn

   Replace <path_to_your_vpn_config_file> with the actual path to the downloaded VPN configuration file.

4. Connecting to HTB Labs: After running the command, enter credentials if required. Once authenticated, the VPN connection will be established, placing you in the same IP subnet as the vulnerable machines.

Abbreviated Name for a Tunnel Interface

When the VPN connection is established, the output typically shows the creation of a tunnel interface. The abbreviated name for this tunnel interface is usually displayed as “tun.” This indicates a secure tunnel has been created between your device and the HTB server, ensuring all data transmitted over this tunnel is encrypted and secure.

Tools for Interacting with the Operating System

To issue commands via the command line, such as starting the VPN connection, use a terminal. A terminal is a command-line interface allowing users to communicate with the operating system by typing instructions. It offers a means of carrying out numerous operations and effectively managing the system.

Testing Connection with ICMP Echo Request

To test your connection to the target with an ICMP echo request, use the ping command. This command sends ICMP echo requests to a specific IP address and measures the round-trip time for the response, verifying connectivity with the target.

Finding Open Ports on a Target

To find open ports on a target, use nmap. Nmap is a versatile and widely used network scanning tool that allows discovery of open ports, services, and information about remote systems. It is an essential tool in any penetration tester's arsenal.

Identifying Services on Specific Ports

During scans, various services running on different ports may be identified. For example, port 23/tcp is identified as running the 'telnet' service, which provides a command-line interface to interact with the remote system.

Username for Telnet Login

The username able to log into the target over telnet with a blank password is 'root.' This is typically used for educational purposes to teach users how to use the telnet port, as seen in the HTB Meow machine.

Practical Example: Scanning and Exploiting

Step 1: Scanning the Target

First, scan the target machine to identify open ports and services. Use nmap for this purpose:
bash
$ nmap -sV 10.129.7.49

This command will scan the machine at IP address 10.129.7.49 and provide detailed information about the open ports and services running on it.

Step 2: Identifying Open Ports

The output of the nmap scan might look something like this:
plaintext
Starting Nmap 7.94 ( https://nmap.org ) at 2023-06-28 11:59 +03

Nmap scan report for 10.129.7.49

Host is up (0.13s latency).

Not shown: 999 closed tcp ports (reset)

PORT STATE SERVICE VERSION

23/tcp open telnet Linux telnetd

Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .

Nmap done: 1 IP address (1 host up) scanned in 12.59 seconds

From this output, you can see that port 23/tcp is open and running the 'telnet' service.

Step 3: Logging into Telnet

To log into the target over telnet with a blank password, use the following command:
bash
$ telnet 10.129.7.49

This command will attempt to connect to the machine at IP address 10.129.7.49 using the telnet service. Once connected, interact with the remote system using telnet commands.

Step 4: Exploiting Vulnerabilities

Once logged in, proceed to exploit any vulnerabilities found during the scanning phase. For example, if a service is running on an open port, gain access to the system by exploiting a known vulnerability in that service.

Forming a VPN connection into HTB labs using OpenVPN is a crucial step for any penetration tester looking to practice their skills in a secure and controlled environment. By understanding how to configure and use OpenVPN, as well as other tools like nmap and telnet, effectively scan and exploit machines on HTB, honing skills in the process.