OpenVPN

OpenVPN is a free and open-source virtual private network (VPN) system that implements virtual private network techniques to create secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities. It uses a custom security protocol that utilizes SSL/TLS for key exchange.

Overview

OpenVPN is capable of traversing network address translators (NATs) and firewalls. It was written by James Yonan and is published under the GNU General Public License (GPL). OpenVPN is available on a wide range of operating systems, including Linux, macOS, Windows, and BSD variants, as well as mobile platforms like Android and iOS.

Key Features

• Cross-platform compatibility: OpenVPN supports numerous operating systems.
• Security: Employs SSL/TLS for secure key exchange and authentication. Supports various cipher algorithms.
• NAT and Firewall Traversal: Designed to operate through most NAT configurations and firewalls.
• Flexible Configuration: Highly configurable, allowing users to tailor the VPN connection to specific needs.
• Open Source: The open-source nature allows for community auditing and improvement of the code.
• Extensibility: Supports various authentication methods, including passwords, certificates, and smart cards.
• Bridged or Routed VPN: Can be configured as either a bridged VPN (Layer 2) or a routed VPN (Layer 3).
• Remote Access and Site-to-Site VPN: Supports both remote access scenarios (connecting individual clients to a network) and site-to-site VPNs (connecting entire networks).

Architecture

OpenVPN operates using a client-server model. A server runs on a machine with access to the desired network, and clients connect to this server. The communication between the client and server is encrypted, creating a secure tunnel.

Uses

OpenVPN is commonly used for:

• Secure remote access: Allowing users to securely access a private network from a remote location.
• Bypassing censorship: Circumventing internet censorship by routing traffic through a server located in a different region.
• Protecting privacy: Encrypting internet traffic to protect user privacy.
• Securing public Wi-Fi connections: Protecting data when using public Wi-Fi networks.
• Connecting geographically dispersed networks: Creating secure connections between networks located in different physical locations.

Alternatives

Alternatives to OpenVPN include:

• IPsec
• WireGuard
• L2TP/IPsec
• SSTP