An In-Depth Look at SSTP (Secure Socket Tunneling Protocol)

Miklos Zoltan

By Miklos Zoltan . 15 June 2024

Founder - Privacy Affairs

Justin Oyaro

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As a cybersecurity enthusiast and a frequent user of various online services, I’ve come to appreciate the importance of secure and reliable VPN protocols.

One such protocol that has caught my attention is SSTP (Secure Socket Tunneling Protocol).

SSTP stands out for its robust security features and seamless integration with Windows systems.

In this article, I’ll delve into the details of SSTP, explaining its key features, how it works, and its advantages and disadvantages.

What is SSTP?

SSTP is a VPN protocol developed by Microsoft and introduced with Windows Vista SP1.

It uses SSL (Secure Sockets Layer) over port 443 to create a secure and encrypted connection between the client and the server.

SSL is the same technology used to secure websites, which means SSTP can bypass many firewalls and network restrictions that block other VPN protocols.

Key Features of SSTP

1. Security:

SSTP offers strong security by leveraging SSL/TLS encryption. This encryption ensures that data transmitted over the VPN is protected from eavesdropping and tampering.

SSTP typically uses 2048-bit SSL/TLS certificates for authentication and 256-bit SSL keys for encryption, making it highly secure.

2. Firewall and Proxy Bypass:

One of the standout features of SSTP is its ability to bypass firewalls and network proxies.

Since it uses port 443, which is the standard port for HTTPS traffic, SSTP can navigate through network environments that restrict other VPN protocols. This makes it a reliable choice for users in restrictive regions.

3. Integration with Windows:

SSTP is natively supported on Windows Vista and later versions.

This deep integration with Windows means that setting up an SSTP VPN is straightforward for Windows users, without the need for additional software or complex configurations.

How Does SSTP Work?

SSTP establishes a secure connection by encapsulating PPP (Point-to-Point Protocol) traffic within an SSL/TLS channel. Here’s a step-by-step overview of how SSTP works:

1. Establishing the Connection:

The client initiates a connection to the VPN server over port 443. This initial handshake uses SSL/TLS to create a secure channel.

2. Authentication:

The server presents its SSL/TLS certificate to the client. The client verifies the certificate to ensure it is connecting to a legitimate server. This process prevents man-in-the-middle attacks.

3. Session Establishment:

Once the server is authenticated, the client and server negotiate encryption parameters and establish an SSL/TLS session. This session is used to encrypt all data transmitted between the client and server.

4. Data Transmission:

The client encapsulates PPP frames within the SSL/TLS channel. These frames are then transmitted securely to the server, ensuring data privacy and integrity.

Advantages of SSTP

1. Strong Security:

SSTP’s use of SSL/TLS provides robust encryption and secure authentication, ensuring that data remains confidential and tamper-proof.

2. Firewall and Proxy Bypass:

SSTP’s ability to use port 443 allows it to bypass firewalls and proxies that might block other VPN protocols, making it a versatile choice for accessing restricted networks.

3. Seamless Windows Integration:

For Windows users, SSTP offers a native and easy-to-configure VPN solution, reducing the need for third-party software and simplifying the setup process.

4. Reliable Performance:

SSTP is known for providing stable and reliable connections, even in network environments with strict security measures.

Disadvantages of SSTP

1. Limited Cross-Platform Support:

While SSTP is natively supported on Windows, it has limited support on other platforms such as macOS, Linux, and mobile devices.

Users of these platforms may need additional software or may prefer other VPN protocols with broader compatibility.

2. Proprietary Protocol:

As a Microsoft-developed protocol, SSTP is proprietary, which means it is not open-source. Some users and organizations prefer open-source protocols like OpenVPN for transparency and community-driven security audits.

3. Dependence on SSL/TLS:

While SSL/TLS is generally secure, its security is only as strong as the implementation. Poorly configured SSL/TLS settings or weak certificates can potentially undermine SSTP’s security.

My Personal Experience with SSTP

In my experience, SSTP has proven to be a reliable and secure VPN protocol, particularly for Windows environments. I’ve used SSTP to securely connect to corporate networks and access resources while traveling.

Its ability to bypass restrictive firewalls has been invaluable in situations where other VPN protocols were blocked.

However, I’ve also encountered challenges when trying to use SSTP on non-Windows devices, which required additional configuration and third-party software.

VPNs That Use SSTP (Secure Socket Tunneling Protocol)

As someone who frequently relies on VPNs for secure and private internet access, I’ve explored various options that support SSTP.

While SSTP is not as commonly supported as some other VPN protocols like OpenVPN or IKEv2, there are still several reputable VPN services that offer SSTP for users who need it. Here are a few VPNs that support SSTP:

1. ExpressVPN


ExpressVPN is one of the best VPNs around and is renowned for its high-speed servers, robust security features, and excellent customer service. It offers a range of VPN protocols, including SSTP, which is particularly beneficial for users who need to bypass restrictive firewalls and access blocked content.


  • AES-256 Encryption: ExpressVPN uses strong AES-256 encryption, ensuring that your data is highly secure.
  • Network Lock (Kill Switch): This feature prevents data leaks by blocking all internet traffic if the VPN connection drops unexpectedly.
  • Wide Server Network: With over 3,000 servers in 94 countries, ExpressVPN provides extensive coverage and fast connection speeds.
  • Cross-Platform Support: Although SSTP is primarily beneficial for Windows users, ExpressVPN offers support for various platforms, including Windows, macOS, Linux, iOS, and Android.

Personal Experience:

I’ve found ExpressVPN to be incredibly reliable when using SSTP, especially in environments with strict network controls. The setup process is straightforward, and the performance has been consistently strong.

2. NordVPN


NordVPN is another top-tier VPN service known for its comprehensive security features and user-friendly interface. While it predominantly promotes its use of OpenVPN and IKEv2/IPsec, NordVPN also supports SSTP for users who require it.


  • Double VPN: For added security, NordVPN can route your traffic through two VPN servers, providing an extra layer of encryption.
  • CyberSec: This feature blocks ads and protects against malware and phishing attempts.
  • No-Logs Policy: NordVPN has a strict no-logs policy, ensuring that your online activities are not recorded.
  • Extensive Server Network: With over 5,500 servers in 60 countries, NordVPN offers excellent global coverage.

Personal Experience:

I’ve used NordVPN with SSTP to access services that are typically blocked by network administrators. The connection has been stable and secure, and the user interface makes it easy to switch between different VPN protocols.

3. PureVPN


PureVPN is a versatile VPN service that supports a wide range of protocols, including SSTP. It is known for its wide server network and strong focus on user privacy and security.


  • 256-Bit Encryption: PureVPN uses strong encryption to protect your data.
  • Dedicated IP Addresses: For users who need a consistent IP address, PureVPN offers dedicated IP options.
  • Split Tunneling: This feature allows you to route some of your traffic through the VPN while letting other traffic access the internet directly.
  • Multi-Platform Support: PureVPN supports Windows, macOS, Linux, iOS, and Android, making it a flexible choice for users with multiple devices.

Personal Experience:

PureVPN has been effective for me when using SSTP, especially in scenarios where bypassing firewalls is necessary. The setup process is user-friendly, and the service provides detailed guides for configuring SSTP on various devices.


Overview: is a privacy-focused VPN service that offers support for several VPN protocols, including SSTP. It is known for its commitment to maintaining user privacy and providing high-speed connections.


  • Strong Encryption: uses strong encryption standards to ensure your data remains private and secure.
  • Zero Logs Policy: does not store any logs of your online activities, ensuring your privacy is protected.
  • Free Plan Available: offers a limited free plan, making it a good option for users who want to test the service before committing to a paid plan.
  • Multiple Protocols: In addition to SSTP, supports OpenVPN, IKEv2, WireGuard, and SoftEther.

Personal Experience: has proven to be a reliable option for using SSTP, particularly when accessing networks with strict security measures. The service is fast and secure, and the customer support team is responsive and helpful.


While SSTP may not be as widely supported as some other VPN protocols, there are several reputable VPN services that offer it for users who need a reliable and secure way to bypass firewalls and access restricted content.

ExpressVPN, NordVPN, PureVPN, and are all excellent choices that provide robust security features, extensive server networks, and user-friendly interfaces.

Based on my experience, these VPNs have consistently delivered strong performance and reliable connections when using SSTP.

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