OpenVPN on a Nessus Linux VM

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Step-by-Step Guide to Install OpenVPN on Nessus Linux VM:

  1. Update the System: First, make sure your system is up to date. Open a terminal on the Nessus Linux VM and run:bashCopy codesudo apt-get update sudo apt-get upgrade
  2. Install OpenVPN: Install the OpenVPN client on your Linux VM. For Debian/Ubuntu-based systems, use the following command:bashCopy codesudo apt-get install openvpn For RedHat/CentOS-based systems, use:bashCopy codesudo yum install openvpn
  3. Obtain the VPN Configuration File: You need the .ovpn configuration file from your network administrator. This file contains the settings needed to establish the VPN connection.
    • Place the .ovpn file in a directory on your system. For example, /etc/openvpn/ (you can create a directory if it doesn’t exist).
  4. Start OpenVPN: To initiate the VPN connection, use the following command in the terminal (replace /path/to/your/file.ovpn with the actual file path of your .ovpn configuration):bashCopy codesudo openvpn --config /path/to/your/file.ovpn You may be prompted to enter your username and password (if required by your VPN configuration).
  5. Check VPN Connection: After connecting, verify that the VPN connection is active and the VM can route through the VPN.To check the network interface and IP addresses, run:bashCopy codeifconfig You should see a new network interface (often tun0) if the VPN connection is successful.
  6. Start OpenVPN on Boot (Optional): If you want the VPN to start automatically when the system boots, you can enable and start the OpenVPN service.For Debian/Ubuntu systems:bashCopy codesudo systemctl enable openvpn@<config_file_name> sudo systemctl start openvpn@<config_file_name> For RedHat/CentOS systems:bashCopy codesudo systemctl enable openvpn@<config_file_name> sudo systemctl start openvpn@<config_file_name> Replace <config_file_name> with the actual name of your .ovpn configuration file (without the .ovpn extension).

7. Verify VPN Connection for Nessus Scans:

Once the VPN is established, you can perform vulnerability scans using Nessus by targeting the internal network that is now accessible via the VPN connection.

To confirm connectivity between your Nessus Linux VM and the remote systems, you can run a simple ping or use nmap to verify the open ports on your target systems.

bashCopy codeping <target_ip>
nmap <target_ip>

This should establish the VPN connection on your Nessus Linux VM and allow you to access remote targets for vulnerability scanning.

If you encounter the error “No match for argument: openvpn” while trying to install OpenVPN, it’s likely that the OpenVPN package is either not available in your default repositories or you might need to enable additional repositories depending on your Linux distribution.

Here are steps to resolve this issue:

1. For RHEL/CentOS/Fedora-based Systems (yum/dnf)

If you’re using a RedHat/CentOS/Fedora distribution, OpenVPN might not be available by default in your repository. Follow these steps:

Enable EPEL Repository (CentOS/RHEL 7/8):

  1. First, make sure the EPEL (Extra Packages for Enterprise Linux) repository is enabled:bashCopy codesudo yum install epel-release # For RHEL 7/CentOS 7 sudo dnf install epel-release # For RHEL 8/CentOS 8/Fedora
  2. After enabling EPEL, install OpenVPN:bashCopy codesudo yum install openvpn # CentOS/RHEL 7 sudo dnf install openvpn # CentOS/RHEL 8/Fedora
  3. If you still see issues, try installing the OpenVPN 3 client from the EPEL repository:bashCopy codesudo yum install openvpn3

For RHEL 8+ / CentOS 8+ / Fedora:

If you’re using RHEL 8 or CentOS 8 and facing issues, try enabling additional repositories like RHEL CodeReady or using dnf to ensure OpenVPN is installed.

2. For Ubuntu/Debian-based Systems (apt)

If you are on Ubuntu or Debian and see the “No match for argument: openvpn” error, it could mean that your package list is outdated or OpenVPN isn’t found in your enabled repositories. Here’s what to do:

  1. Update the Package List: Run the following command to ensure your package list is up-to-date:bashCopy codesudo apt-get update
  2. Install OpenVPN: After updating the package list, install OpenVPN using:bashCopy codesudo apt-get install openvpn
  3. If OpenVPN is still not found, you can install it from the universe repository:bashCopy codesudo add-apt-repository universe sudo apt-get update sudo apt-get install openvpn

3. Manual Installation (if package manager fails)

If you continue to experience issues, you can manually download and install OpenVPN from the official OpenVPN site or use the OpenVPN 3 client, which may be more widely supported.

Download OpenVPN from OpenVPN Official Website:

  1. Go to OpenVPN Downloads and choose the Linux version suitable for your system.
  2. Follow the installation instructions specific to your distro.

For example, on Ubuntu:

  • Download the OpenVPN .deb file and install it manually:bashCopy codewget https://swupdate.openvpn.org/community/releases/openvpn3-<version>.tar.gz tar -xvzf openvpn3-<version>.tar.gz cd openvpn3-<version> sudo ./configure sudo make sudo make install

4. Verify Installation:

Once OpenVPN is successfully installed, verify the installation with:

bashCopy codeopenvpn --version

This should confirm that OpenVPN is installed and provide its version information.

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