Is OpenVPN still secure in 2026?

Yes. OpenVPN with AES-256-GCM encryption remains extremely secure. While its codebase is large, it has been extensively audited over 20+ years. No practical vulnerabilities have been found in the core protocol.

Should I use OpenVPN TCP or UDP?

Use UDP for better speed and performance. Use TCP only when you need to bypass firewalls or in networks that block UDP VPN traffic. TCP adds overhead for error correction that reduces speed.

Why is OpenVPN slower than WireGuard?

OpenVPN runs in userspace (not the kernel), uses heavier encryption overhead, has larger packet sizes, and requires more CPU processing. WireGuard operates at the kernel level with streamlined cryptography, resulting in 2-3x faster speeds.

OpenVPN Protocol Explained: The Industry Standard Since 2001

OpenVPN has been the gold standard VPN protocol for over two decades. It is open-source, extensively audited, and supported by virtually every VPN provider. While WireGuard has surpassed it in speed, OpenVPN remains the most versatile and battle-tested protocol available, particularly valued for its TCP support and configurability.

Speed

7/10

Security

10/10

Stability

10/10

Year

2001

Open Source

Yes

How OpenVPN Works

OpenVPN creates a TLS-encrypted tunnel using the OpenSSL library. It can operate in either UDP mode (faster) or TCP mode (more reliable, harder to block). Running on TCP port 443 makes OpenVPN traffic indistinguishable from HTTPS, making it effective at bypassing firewalls and censorship. The protocol supports a wide range of encryption algorithms and authentication methods.

Technical Details

Encryption

AES-256-GCM (default), supports multiple ciphers including AES-128, ChaCha20-Poly1305. RSA or ECDSA for authentication. TLS for key exchange.

Ports

TCP (port 443) or UDP (port 1194), fully configurable

Developer

James Yonan / OpenVPN Inc.

Best For

Maximum compatibility, firewall bypassing (TCP mode), high-security environments

Advantages & Disadvantages

Advantages

+ Most extensively audited VPN protocol in existence
+ Supports both TCP and UDP modes
+ TCP port 443 makes traffic look like HTTPS
+ Highly configurable encryption options
+ Works on virtually every platform
+ Open-source with 20+ years of real-world use
+ Excellent firewall and censorship bypass on TCP

Disadvantages

- Significantly slower than WireGuard (30-50% speed difference)
- 600,000+ lines of code -- larger attack surface
- Higher CPU usage and battery drain
- Slower connection times (5-15 seconds typical)
- Complex configuration for manual setups
- Runs in userspace, not kernel-level

VPNs That Support OpenVPN

NordVPNExpressVPNSurfsharkCyberGhostProton VPNPIAMullvadWindscribeIPVanishNearly all VPN providers

Our Verdict on OpenVPN

OpenVPN remains essential for specific use cases: bypassing firewalls with TCP port 443, high-security environments that require algorithm flexibility, and legacy systems. For general use, WireGuard is the better choice in 2026. However, OpenVPN's track record and versatility make it a critical fallback protocol.

Frequently Asked Questions

Is OpenVPN still secure in 2026?: Yes. OpenVPN with AES-256-GCM encryption remains extremely secure. While its codebase is large, it has been extensively audited over 20+ years. No practical vulnerabilities have been found in the core protocol.
Should I use OpenVPN TCP or UDP?: Use UDP for better speed and performance. Use TCP only when you need to bypass firewalls or in networks that block UDP VPN traffic. TCP adds overhead for error correction that reduces speed.
Why is OpenVPN slower than WireGuard?: OpenVPN runs in userspace (not the kernel), uses heavier encryption overhead, has larger packet sizes, and requires more CPU processing. WireGuard operates at the kernel level with streamlined cryptography, resulting in 2-3x faster speeds.

More Protocols

WireGuard IKEv2/IPSec Lightway (ExpressVPN)NordLynx (NordVPN)All protocols