Defeat censorship with Stealth, our new VPN protocol

We’ve developed a new VPN protocol, Stealth, that can avoid detection and let you bypass internet censorship and VPN blocks.

We’re pleased to announce Stealth, a new, undetectable VPN protocol that can bypass most firewalls and VPN blocking methods. You’ll be able to bypass advanced VPN blocks, access censored sites, and communicate with people on social media, even if your government is trying to restrict access.

Why is Stealth needed?

In 2017, we launched Proton VPN because there was no trustworthy, reliable, and freely available VPN service. Our motivation was simple. Because our services, such as Proton Mail, play a crucial role in ensuring freedom and privacy worldwide, we knew authoritarian governments would eventually try to block them.

But with Proton VPN, people can bypass those blocks and continue using Proton Mail. Over the past few years, Proton VPN has become an essential tool, helping ensure the free flow of information for tens of millions of people during crises and wars around the world.

Since we launched Proton VPN, we’ve continuously worked on technology to bypass surveillance and censorship. For example, in 2017, we launched Secure Core VPN, which provides greater privacy than typical VPN services.

In 2020, we launched alternative routing(new window), which bypasses VPN blocks by re-routing our connections over other hard-to-trace paths. Finally, in 2021, we released VPN Accelerator, a unique technology that provides connection speeds that are up to 400% faster, which is critically important for users in far-flung regions with slower internet.

As we have stepped up our efforts to build a more censorship-resistant VPN, authoritarian governments have also stepped up their efforts to block VPNs. Traditional VPN protocols (such as OpenVPN, IKEv2, and WireGuard) are relatively easy to recognize on a network. And as deep packet inspection (DPI) technology becomes more widespread, it will be easier and easier for authoritarian governments to detect and block VPNs using these protocols.

For years there have been various projects to try to obfuscate existing VPN protocols, but many of them are hacks on top of existing protocols that unfortunately no longer work very well.

We designed our Stealth protocol from the ground up to not have these issues. With Stealth enabled, your Proton VPN connection will be almost completely undetectable.

Stealth is available on all Proton VPN plans, including our Free plan, because everyone deserves online freedom. For now, you can use Stealth on our Android, macOS, and iOS apps.

How do I use Stealth?

To activate Stealth, open the Proton VPN app on your device.

  • On Android,  tap  →  Settings → Advanced → Protocol and choose Stealth.
  • On iOS and iPadOS, tap Settings → Security options → Protocol and choose Stealth.
  • On macOS, ProtonVPN in the macOS taskbar → PreferencesConnectionProtocol and select Stealth from the dropdown menu.

Stealth is not yet available on our Windows or Linux apps.

Learn more about changing VPN protocols

How does the Stealth VPN protocol work?

Stealth uses obfuscation to hide your VPN connection from censors. The general idea is to make VPN traffic look like “normal” traffic — or common HTTPS connections. Stealth does this by using obfuscated TLS tunneling over TCP. This is different from most popular VPN protocols that typically use UDP, making them easier to detect and block. Without going into too much detail, Stealth also establishes VPN connections in a specific and unique way that avoids alerting internet filters.

Despite these obfuscation features, the Stealth VPN protocol is also optimized for high performance and is compatible with our VPN Accelerator technology. Coupled with our lightweight internals, Stealth can achieve higher performance than older obfuscated VPN protocols that are generally built on top of OpenVPN over TCP.

The fight continues

We want to thank the members of the Proton community who helped us test the Stealth VPN protocol over the last couple of months. They live under restrictive censorship regimes, and Stealth would have been impossible to develop without their assistance. Thank you.

However, in the constantly evolving battle for online freedom, our work is not finished. Accordingly, we designed Stealth to be an extensible and adaptable VPN protocol that is flexible enough to meet new challenges.

The cause of freedom has no borders, and we must stand together for it to succeed. Tools like Proton VPN play a vital role in keeping the internet free. Our investment in technologies like Stealth is part of our commitment to provide internet privacy to everyone, regardless of their ability to pay.

Proton VPN will always be free, but if you would like to support our mission to keep the internet free and open to all, you can subscribe to a paid plan which offers even faster speeds and premium features.

P.S. We want to say thanks to the hundreds of Proton VPN community members who suggested names for our new protocol. Your top choice was Neutrino, which we liked a lot because of the connection to physics. And neutrinos can pass through all matter, making it even more appropriate. 

Unfortunately, we felt this name might cause confusion with a Web3 project, so we picked Stealth instead. This was another popular community suggestion, and its meaning is more obvious to those less familiar with physics.

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