What is OpenVPN?
OpenVPN is an open-source VPN protocol that has been the industry standard for secure VPN connections for two decades, known for its strong security, flexibility, and wide compatibility across platforms.
OpenVPN is an open-source VPN tunneling protocol first released in 2001. For much of VPN history, it was considered the gold standard — offering a powerful combination of security, configurability, and cross-platform compatibility. While newer protocols like WireGuard have taken the speed crown, OpenVPN remains a cornerstone of the VPN industry and is still widely deployed.
How OpenVPN Works
OpenVPN uses the OpenSSL library and supports AES-256 encryption along with a variety of ciphers. It can operate over both UDP (faster, better for streaming and gaming) and TCP (more reliable, better for bypassing firewalls). It supports Perfect Forward Secrecy through ephemeral key exchanges, meaning captured traffic can't be decrypted retroactively.
OpenVPN vs. WireGuard
| OpenVPN | WireGuard | |
|---|---|---|
| Code size | ~70,000+ lines | ~4,000 lines |
| Speed | Moderate | Very fast |
| Security | Excellent | Excellent |
| Auditability | Complex | Simple |
| Mobile performance | Adequate | Excellent |
| Age | 2001 | 2019 |
OpenVPN's larger codebase makes it harder to audit for vulnerabilities. WireGuard's lean design is easier to review thoroughly — but OpenVPN's long track record and extensive real-world use means its behavior is extremely well understood.
OpenVPN and Obfuscation
One of OpenVPN's practical advantages is how well it integrates with obfuscation tools. Because its traffic can be wrapped in additional SSL/TLS layers, it's commonly used in countries that censor or restrict VPN use. Obfsproxy and similar tools disguise OpenVPN traffic as regular HTTPS browsing.
Who Uses OpenVPN?
Almost every major VPN provider supports OpenVPN: NordVPN, ExpressVPN, ProtonVPN, Private Internet Access, and Mullvad all offer it. Many providers are shifting default recommendations to WireGuard for speed, but OpenVPN remains available as a security-focused option.
OpenVPN is also available as a standalone client, meaning you can configure it manually with any compatible VPN provider — useful for businesses running their own VPN servers or privacy-focused users who want full control.
OpenVPN TCP vs. UDP
- UDP mode — Lower latency, better for video, gaming, and general browsing
- TCP mode — More reliable over unstable connections; better at bypassing restrictive firewalls since TCP port 443 (used by HTTPS) is rarely blocked
Most VPN clients default to OpenVPN UDP and only switch to TCP if the connection fails or is blocked.