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How To Authenticate with OpenVPN Server Using Username and Password in Ubuntu

Ubuntu 16

In this article, we will guide you through the process of authenticating with an OpenVPN server using a username and password in Ubuntu. This process involves configuring the OpenVPN server to allow password authentication and setting up your Ubuntu client to connect to the server using your credentials.

It’s important to note that while this method simplifies the authentication process, it’s not as secure as using a client certificate. Therefore, we highly recommend using this method only in secure, trusted networks.

Quick Answer

To authenticate with an OpenVPN server using a username and password in Ubuntu, you need to configure the server to allow password authentication and set up the client to connect using your credentials. This involves modifying the server configuration file and adding a line to the client configuration file. Once configured, you can connect to the VPN server using the OpenVPN client and entering your username and password when prompted.

Prerequisites

Before we begin, ensure that you have the following:

  1. Ubuntu 18.04 or 20.04 installed on your client machine.
  2. OpenVPN server installed and configured.
  3. Root or sudo access on both the client and server machines.

Server Configuration

First, we need to configure the OpenVPN server to allow password authentication.

  1. Open the server configuration file with a text editor. In this example, we’ll use nano:
sudo nano /etc/openvpn/server.conf
  1. Add or uncomment the following lines:
auth-user-pass-verify /etc/openvpn/checkpsw.sh via-env
script-security 3
client-cert-not-required
username-as-common-name

Here, auth-user-pass-verify specifies the script to verify the username and password. script-security 3 allows OpenVPN to call external programs. client-cert-not-required and username-as-common-name instruct the server to authenticate clients using username/password only.

  1. Save the changes and exit the editor.
  2. Restart the OpenVPN service:
sudo systemctl restart openvpn@server

Client Configuration

Next, we need to set up the Ubuntu client to connect to the OpenVPN server using a username and password.

  1. Install the OpenVPN client on your Ubuntu machine:
sudo apt-get install openvpn
  1. Download or copy the client configuration file from your OpenVPN server. This file usually has the extension .ovpn.
  2. Open the client configuration file with a text editor:
sudo nano client.ovpn
  1. Add or uncomment the following line:
auth-user-pass

This line instructs the client to prompt for a username and password when connecting to the server.

  1. Save the changes and exit the editor.
  2. Connect to the VPN server:
sudo openvpn --config client.ovpn

You should be prompted for your username and password. After entering your credentials, you should be connected to the VPN server.

Conclusion

In this article, we’ve shown you how to authenticate with an OpenVPN server using a username and password in Ubuntu. While this method is simpler than using client certificates, it’s also less secure. Therefore, we recommend using it only in secure, trusted networks.

Remember to always keep your OpenVPN server and client software up-to-date to benefit from the latest security patches and improvements. For more information on OpenVPN, you can check out the official OpenVPN documentation.

Can I use this method to authenticate with an OpenVPN server on other Linux distributions?

Yes, you can use this method to authenticate with an OpenVPN server on other Linux distributions as long as you have the necessary prerequisites installed (such as OpenVPN client and server) and make the appropriate configuration changes.

Can I use this method to authenticate with an OpenVPN server on Windows or macOS?

No, this method is specific to Ubuntu and other Linux distributions. Windows and macOS have their own methods for authenticating with an OpenVPN server.

Is it possible to use both username/password authentication and client certificates for authentication?

Yes, it is possible to use both methods for authentication. You would need to configure the OpenVPN server to allow both types of authentication and set up the client accordingly. However, using client certificates provides a higher level of security.

Can I use a different text editor instead of nano to edit the server and client configuration files?

Yes, you can use any text editor of your choice to edit the server and client configuration files. Just replace "nano" with the command to open the text editor of your choice in the provided instructions.

Is it necessary to restart the OpenVPN service after making changes to the server configuration file?

Yes, it is necessary to restart the OpenVPN service after making changes to the server configuration file in order for the changes to take effect. You can do this by running the command sudo systemctl restart openvpn@server.

Can I connect to multiple OpenVPN servers using this method?

Yes, you can connect to multiple OpenVPN servers using this method. You would need to have separate client configuration files for each server and specify the appropriate file when connecting to each server.

Is it possible to save the username and password for automatic authentication?

Yes, it is possible to save the username and password for automatic authentication. You can add the auth-user-pass line to the client configuration file without any values, and the OpenVPN client will use a saved password file for authentication. However, note that this may compromise the security of your credentials.

What should I do if I forget my OpenVPN server username and password?

If you forget your OpenVPN server username and password, you will need to contact the administrator of the server to reset your credentials. They will be able to assist you in regaining access to the server.

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