OpenVPN

OpenVPN is an open-source server that provides secure tunneling for remote network access. It functions as a daemon that creates encrypted point-to-point or site-to-site connections over the internet, allowing remote clients to access private network resources as if they were physically connected to the local area network.

The software is deployed using a server and client architecture. It is typically installed on a server that acts as the gateway to the protected network, while clients install the software on their local machines to establish the encrypted tunnel. It supports deployment across multiple operating systems, including Linux and Windows, and is managed primarily through configuration files and command line interfaces.

Key features

• Secure tunneling daemon for remote network access
• Support for X509 certificate based authentication
• Custom authentication tests via the tls-verify option
• Compatibility with RSA keys and certificates
• Cross platform support for Linux and Windows
• Flexible configuration through dedicated config files
• Integration with the SSL protocol for encryption
• Support for site to site and point to point connections

OpenVPN relies on a custom protocol based on SSL for its security layer, ensuring that data transmitted between the client and server remains encrypted. The architecture allows administrators to implement customized authentication checks using external scripts, such as Perl, to verify specific fields within X509 certificates before granting access. This makes the software suitable for environments that require strict control over which devices or users can enter the network.

The project maintains a modular approach by separating the core daemon from auxiliary tools. For example, certificate management is handled by the easy-rsa subproject, and network driver support for Windows is provided through the tap-windows project. This separation allows for independent updates to the underlying network drivers and the security protocols used for key generation.

It serves as a foundational tool for organizations requiring self-hosted virtual private networks to secure data transmission and manage remote access.