What Is OpenVPN

What Is OpenVPN? A Guide to the VPN Protocol in 2024

Last update: October 3, 2024

Quick Summary: What Is OpenVPN?

OpenVPN is a secure and versatile VPN protocol used in popular VPN services like ExpressVPN, NordVPN and Surfshark. It offers flexible configurations and strong community support, making it a reliable choice for secure online connections.

OpenVPN is a widely used VPN protocol known for its security and versatility. If you have ever set up a connection on your device to one of the best VPNs, there is a high chance that you have come across it. If you’re still confused, follow along as I answer the question, “What is OpenVPN?”

For those new to VPN technology, a VPN protocol, also called a tunneling protocol, is a set of rules and specifications that govern how data is encrypted and transmitted between your device and the VPN server. See our “What Is a VPN?” article if you haven’t heard of this privacy technology.

Each VPN protocol employs its own set of rules and technologies, so privacy, security and internet speeds vary from one protocol to another. In this article, I will discuss everything you should know about what OpenVPN is, how it works, how it stacks up against other VPN protocols and much more. 


What Is OpenVPN?

The OpenVPN tunneling protocol is an open-source protocol used in many popular virtual private network (VPN) solutions, including ExpressVPN, NordVPN and Surfshark. A VPN protocol is a set of rules that creates an encrypted tunnel between your device and your VPN server, ensuring the two can communicate without being configured beforehand.

Is OpenVPN a VPN? 

No, OpenVPN is not an out-of-the-box VPN service like ExpressVPN or NordVPN. It’s a secure VPN protocol that you can activate in your VPN client settings. OpenVPN software, which is open-source and free to download, allows you to create your own VPN and connect to any OpenVPN server. 


OpenVPN: How It Works 

OpenVPN uses advanced encryption techniques to secure your internet connection. Here’s a step-by-step breakdown of how it works.

Authentication Methods 

Before connecting your device to a VPN server, OpenVPN authenticates the identities of both your device and the server. In a typical credential-based authentication process, the VPN server verifies your username and password before allowing the connection. A digital certificate-based authentication process uses digital certificates to verify your device and the VPN server.

Other authentication methods OpenVPN can use include pre-shared keys and public key infrastructure (PKI) handled by RSA — a public-key cryptosystem. 

Client-Server Tunnel

Once OpenVPN has verified the trustworthiness of the VPN client (that’s you, the user) and the VPN server, it creates an encrypted tunnel using Secure Sockets Layer/Transport Layer Security (SSL/TLS) as its security protocol.

Data Encryption

After the tunnel is established, OpenVPN encapsulates data packets by adding routing and security information layers. Then, OpenVPN encrypts data packets using the OpenSSL library

OpenVPN allows customization of encryption methods, supporting various cryptographic algorithms and key lengths to meet different security needs. Most VPN clients build a custom security protocol that uses AES-256-GCM for encryption.

Data Transmission to a VPN Server

Once OpenVPN has encapsulated and encrypted your data, it transmits it to the VPN server through the established tunnel. When it reaches the server, your data is decrypted and sent to its intended destination. This process hides your IP address, making only the VPN server’s IP visible to the outside world so you can circumvent surveillance or get Netflix unblocked.


What Is OpenVPN Used For?

OpenVPN is used to secure connections and protect data. The following are key OpenVPN use cases:


OpenVPN UDP vs OpenVPN TCP

The OpenVPN protocol can operate over two transmission protocols: User Datagram Protocol (UDP) and Transmission Control Protocol (TCP). All the best VPNs on the market allow you to select either UDP or TCP for your VPN connection. 

The OpenVPN UDP protocol sends data in a stream without establishing a permanent connection. It still must authenticate the destination server, but it doesn’t build a permanent channel like TCP does. This approach allows for faster data transmission, as it bypasses the need for handshakes or acknowledgments between the sender and receiver.

However, it also means that if packets are lost or arrive out of order, they won’t be automatically retransmitted, thus affecting the transport protocol’s reliability in unstable network conditions.

OpenVPN TCP establishes a connection through a handshake before data transmission begins. It guarantees reliable, error-free packet delivery and retransmits lost packets. However, its acknowledgment and error correction processes introduce delays, making it slower than OpenVPN UDP. 

Both OpenVPN UDP and TCP are perfect for obfuscation — the practice of disguising VPN traffic to make it less detectable by firewalls or network-monitoring systems.

TCPUDP
High reliability due to packet retransmissionLower reliability; no retransmission of lost packets
Sequential packet delivery, making it ideal for email, web browsing and other static usesPackets moved in a stream, making it suitable for streaming, gaming, VoIP and other dynamic uses
Waits until buffer space is available before sending packetsNo flow control
Lower speed due to packet retransmission overheadHigher speed due to no-overhead packet retransmission

OpenVPN vs Other Protocols: Which Is Best?

OpenVPN excels at compatibility. It supports a wide range of devices and routers, and offers strong security and fast speeds. 

WireGuard, a newer protocol, offers superior speeds and security compared to OpenVPN thanks to its faster authentication and lean codebase. However, it doesn’t support as many operating systems and devices as OpenVPN. IKEv2/IPsec may be a better choice for mobile devices because of its auto-reconnect feature, speed and stability. 

The best protocol depends on how you want to use the VPN. To provide optimum VPN benefits, all leading VPN providers have an auto-connect protocol feature that helps you pick the fastest available VPN protocol for your chosen VPN server.

Here’s a quick comparison of different types of VPN protocols and how they stack up against each other. 

Protocol:SecuritySpeedEncryption
OpenVPNHighFastAES-256
WireGuardHighFastChaCha20
L2TPHighGoodAES-256,
3DES
PPTPWeakFastMPPE
IKEv2GoodFastAES-256,
3DES
ShadowsocksAverageFastAEAD_CHACHA20_POLY1305,
AEAD_AES_256_GCM
SSTPAverageAverageAES-256

OpenVPN Benefits & Challenges 

OpenVPN is a reliable VPN protocol. It offers good security, excellent flexibility and the possibility of obfuscation, but it’s reasonable to consider the pros and cons before making it your default VPN protocol. 

Pros
  • Diverse connection modes (point-to-point or site-to-site)
  • Supports strongest available encryption, including AES-256
  • Stable connections
  • Open-source
Cons
  • Can consume more battery power
  • Speeds can be lower than WireGuard and IKEv2
  • Potential for configuration errors if not using a commercial VPN
  • Complex configuration if you don’t use a commercial VPN like ExpressVPN

Is OpenVPN Safe, Secure & Private?

Yes, the OpenVPN protocol is safe, secure and private. It uses AES 256-bit encryption most often, which modern computers cannot crack. OpenVPN supports perfect forward secrecy, meaning encryption keys are regularly changed. This ensures that hackers can’t decrypt past or future sessions even if they obtain a key.

OpenVPN is also flexible, allowing you to choose between UDP for speed and TCP for stability. Its open-source nature means a large community of OpenVPN developers can review its code, making finding and fixing vulnerabilities easier.


Can I Use OpenVPN for Free? 

Yes, you can use OpenVPN for free. If you have technical skills, you can utilize OpenVPN Connect, a free VPN client developed by the OpenVPN company, or employ the OpenVPN Software Community Edition to create your own VPN and access the OpenVPN protocol at no cost. 

OpenVPN connect settings -- what is openvpn
Set the OpenVPN protocol to TCP for email, web browsing and other static uses.

Additionally, you can use OpenVPN Access Server, a commercial product that allows up to two free simultaneous connections without the need for a paid license.

For an average user who wants a simple plug-and-play solution, an easier method is to use free VPN services like PrivadoVPN or Windscribe that support the OpenVPN protocol. However, these free VPNs often limit your choice of server locations and security features and usually have data caps. 


What Are the Best VPNs That Use the OpenVPN Protocol?

Most reputable VPNs come with OpenVPN. Here’s a quick overview.

ExpressVPN openvpn setting
Turn off “advanced protection” first to select OpenVPN.
NordVPN OpenVPN setting
Turn off “web protection” to use OpenVPN.
surfshark openvpn setting
Surfshark allows you to use OpenVPN without turning off CleanWeb.

Conclusion

OpenVPN’s balance of security, speed and compatibility makes it a top VPN protocol. Remember that the safety of any VPN depends on more than just the protocol, though — it also relies on the provider’s privacy policies and server security.

The PrivacyJournal team has extensively tested ExpressVPN, NordVPN and Surfshark and found them to be perfectly safe when using the OpenVPN protocol.

Do you use OpenVPN? Which VPN protocol is your go-to? I’d love to hear about it in the comments section. Thanks for reading.


FAQ: OpenVPN Explained

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