VPN protocols: OpenVPN (TCP vs. UDP)

Learn more about using OpenVPN and the difference between TCP and UDP.

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OpenVPN protocol

What is OpenVPN?

OpenVPN is a relatively new and highly configurable protocol. The best thing about OpenVPN is that it is open source. “Open” may not sound like a good thing for a privacy tool, but it is actually a huge advantage. If there are any security flaws in the code—and as yet none are known—they will be quickly identified by the open-source community. Paired with a strong encryption algorithm, OpenVPN is one of the most secure VPN protocols available.


  • Open source
  • Extremely secure


  • Not supported on all devices

The difference between TCP vs. UDP

ExpressVPN’s version of OpenVPN supports both UDP and TCP ports. In the ExpressVPN app, OpenVPN is actually referred to as “UDP” or “TCP,” two internet protocols that can greatly affect performance.

What is UDP?

UDP stands for User Datagram Protocol. Though it can be configured to run on any port, OpenVPN runs best on a UDP port. UDP does not allow the recipient to acknowledge receipt of the data or request information to be resent. This allows UDP to establish connections and transfer data faster. Your ExpressVPN app is likely to choose UDP when using OpenVPN. By default, you will experience faster speeds over UDP. On unreliable networks, however, you may have a better experience switching to TCP.

What is TCP?

TCP stands for Transmission Control Protocol. Unlike UDP, TCP carefully checks whether data is received by the recipient in the correct form and order and can request it again. This results in increased reliability at the expense of latency.

Speech bubbles with different VPN protocols.

Other VPN protocols

In addition to offering a standard set of protocols, ExpressVPN built Lightway to outdo them all in speed, reliability, and security. Give it a try to see for yourself. Learn more about Lightway.

If you’re still not sure which VPN protocol to choose, simply let the ExpressVPN app automatically select the best one for you.

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