SSTP: Understanding the Secure Socket Tunneling Protocol

Published on: April 21, 2024

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10 min read

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For German Version

The VPN (Virtual Private Network) protocol known as Secure Socket Tunneling Protocol, or SSTP, builds a tunnel between a client device and a server. SSTP is mostly used to protect distant internet access to private networks. To replace the less secure PPTP and L2TP/IPSec protocols, Microsoft created SSTP. Typically, native Windows VPN connections are secured with SSTP. SSTP is typically utilized to provide safe distant internet access to private networks.

A secure tunnel is created between a client device and a distant server for SSTP to function. The SSL/TLS protocol, which is renowned for having strong security characteristics, is used to establish an SSTP tunnel. Data is securely delivered over the internet and packaged in SSL packets when a user creates a VPN connection using SSTP.

The common HTTPS port (TCP port 443) that SSTP utilizes is frequently permitted by firewalls and is widely accepted. Because it guarantees compatibility in the majority of network settings, this is useful. The data is protected during transmission by the SSL/TLS encryption used in SSTP, which stops both illegal access and eavesdropping.

Furthermore, SSTP is made to function flawlessly with Windows operating systems, which makes it a desirable option for businesses that mostly rely on Windows-based infrastructure. However, it is difficult for businesses that use a variety of operating systems.

The importance of SSTP is demonstrated by its cybersecurity and safe data transfer over networks. Here, you'll discover the essential information you need to know about this crucial topic:

• What does SSTP stand for?
  • Is SSTP a VPN?
• What is SSTP used for?
• What are the advantages of SSTP?
• What are the drawbacks of SSTP?
• What is the difference between PPTP and SSTP?
• What is the difference between L2TP and SSTP?
• What is the difference between OpenVPN and SSTP?
• How secure is the SSTP protocol?
• How to connect to an SSTP server?
• How to create an SSTP VPN connection in Windows 11?
• SSTP vs. PPTP vs. L2TP: Which is Best?

What Does SSTP Stand For?

A type of virtual private network (VPN) tunnel called Secure Socket Tunneling Protocol (SSTP) offers a way to send PPP traffic over an SSL/TLS channel. Transport-level security is offered by SSL/TLS, which includes traffic integrity verification, encryption, and key negotiation. Except for authorized web proxies, SSL/TLS across TCP port 443 (by default; port changeable) enables SSTP to flow past almost all firewalls and proxy servers.

Authentication is required for SSTP servers during the SSL/TLS phase. While authentication is required in the PPP phase, it is optional for SSTP clients to be authorized during the SSL/TLS phase. Support for popular authentication protocols like EAP-TLS and MS-CHAP is made possible via the use of PPP.

Windows, BSD, and Linux may all use SSTP.

SSTP is supported by RouterOS version 5.0, Windows Vista SP1 and later, and SEIL firmware version 3.50. Because of its comprehensive integration with the RRAS architecture in these operating systems, it is compatible with the Windows VPN client, Winlogon or smart card authentication, and remote access rules. Windows Azure uses the protocol for point-to-site virtual networks.

Site-to-site VPN tunnels are often not supported by SSTP; they are primarily meant for remote client access.

The same performance issues that affect other IP-over-TCP tunnels affect SSTP. Performance will often only be considered satisfactory if the non-tunneled network link has enough spare capacity to ensure that the tunneled TCP timers don't expire. If this turns out not to be the case, performance suffers greatly. We refer to this as the "TCP meltdown problem."

Only user authentication is supported by SSTP; computer or device authentication is not supported.

Client devices and servers are connected via a secure VPN tunnel established by the Secure Socket Tunneling Protocol (SSTP). Improving online private network security for remote access is its main goal. As a more reliable alternative to the less secure PPTP and L2TP/IPsec protocols, Microsoft launched SSTP.

It is essential to be aware of SSTP if you use a corporate VPN, as it is frequently used to secure native Windows VPN connections.

Is SSTP a VPN?

Yes. A VPN protocol called Secure Socket Tunneling Protocol (SSTP) builds a tunnel between a client device and a server. SSTP is mostly used to protect distant internet access to private networks.

For secure remote access, including file sharing or connecting to corporate systems, an SSTP VPN is utilized. It is well-liked by Windows users as it was created for Windows operating systems. This is often an option available through the UI of your VPN client. Nonetheless, using a VPN that supports several protocols is recommended.

What is SSTP used for?

A client and a server are necessary for any VPN connection. The connection must be supported, and the protocol must be "agreed" upon by the client and server. Since SSL/TLS is not used by traditional point-to-point tunneling protocol (PPTP) connections, SSTP was created to increase data transfer security and get around firewall restrictions that block particular ports. SSTP employs secure key negotiations, encrypted transfers, and SSL/TLS in contrast to PPTP.

SSL/TLS handshakes are employed in the technology that powers SSTP, which is used for secure communications. It bases the connection on human authentication rather than device authentication, and it utilizes the same port (443) as SSL/TLS. It is more common among internet connections that require more security than standard SSL/TLS connections.

To put it briefly, the Secure Socket Tunneling Protocol (SSTP) creates a secure virtual private network (VPN) tunnel between client devices and servers. Improving online private network security for remote access is its main goal. As a more reliable alternative to the less secure PPTP and L2TP/IPsec protocols, Microsoft launched SSTP.

What are the Advantages of SSTP?

Compared to other VPN protocols, Secure Socket Tunneling Protocol (SSTP) offers a number of benefits. Because it protects your data and identity using robust encryption methods and certifications, it is extremely secure. Furthermore, because SSTP is pre-installed on Windows and is compatible with a wide range of VPN clients and providers, it is simple to set up. It is dependable since it can adapt to changes in the network and instantly reestablish a connection if one does. Lastly, SSTP is covert, as it may pass through filters and restrictions by posing as HTTPS traffic. These are the key advantages of SSTP VPN. The primary benefits of SSTP are as follows:

• Elevated Security: Because SSTP uses SSL/TLS encryption, it is extremely safe from hacker attempts and data breaches. The SSL 3.0 standard is used by SSTP to secure internet traffic. These encryption techniques guarantee that the information will never be obtained by a third party. The degree of encryption is a little higher than typical, though. However, it surpasses the PPTP protocol by much.
• Windows Integration: Configuration and setup are made easier by native support for Windows operating systems. Because Microsoft invented SSTP, the Windows operating system already has it. It is really one of the Windows computers' most dependable protocols. Additionally, it is simple to use on a Windows-based device because Microsoft consistently offers strong support for this protocol.
• Firewall-Friendly: Because SSTP uses TCP port 443 for operation, it can get past a lot of firewalls and proxies, guaranteeing connectivity under a range of network conditions. Any kind of firewall that has been installed dealt with using SSTP, allowing you to visit websites without them being restricted.
• Broad Compatibility: Although SSTP is native to Windows, it can be set up on Linux and macOS, which expands its range of applications.
• Internet Speeds: SSTP is significantly faster than other protocols that have speed limitations. But only in the event that you have enough bandwidth. Because of this, using it to carry out online activities is advised.
• Content Access: Due to regional restrictions, certain online content is inaccessible to users from other countries. These kinds of media can be accessed using an SSTP VPN. With an SSTP VPN, users create whatever kind of material they choose.
• Configuration Simplicity: It's simple to use and set up. Establishing an SSTP VPN connection is typically simple, particularly on Windows-powered devices. Users don't need to install any additional software to establish SSTP VPN connections thanks to Windows' built-in VPN client.
• Stability and Reliability: SSTP is well known for its stability and reliability when it comes to maintaining VPN connections. It is less likely to face interruptions and connection losses and provides a stable and dependable VPN experience. SSTP is renowned for its dependability and capacity to keep connections open even under erratic network circumstances.
• Achievement: Designed to provide maximum efficiency, SSTP makes it easier for data to move across the VPN connection. While real performance may differ based on several variables, SSTP usually provides decent performance for frequent VPN use.
• Compatibility with Network Address Translation (NAT): NAT, which is frequently used in networks to retain IP addresses, is compatible with SSTP. As a result, it may be used in many network contexts.

What are the Drawbacks of SSTP?

It's critical to understand the disadvantages of SSTP before making any decisions. Because it is not open source, proprietary, or controlled by Microsoft, its implementation and code are opaque and may contain backdoors or vulnerabilities. Furthermore, because the TCP and SSL/TLS layers increase connection costs and latency, SSTP is slower than other VPN protocols. Finally, because it is incompatible with some platforms and gadgets, like routers and smart TVs, SSTP is not commonly accessible.

The main disadvantages of SSTP are, as follows:

• Closed source: It is neither visible nor auditable since it is a closed-source, proprietary technology. Furthermore, because it is a closed source, it is impossible to verify if it has any backdoors or other surprises concealed therein.
• Windows-Centric: The main problem with SSTP is that it doesn't work well on other platforms. It is most compatible with Windows devices, which may be a drawback for businesses that use a variety of operating systems. Because of Microsoft's connections to the NSA, there is conjecture that SSTP has backdoors or other security flaws. Every device that isn't Windows-based has trouble using SSTP. This covers Mac OS, Linux, and even some earlier Windows versions. Even if support is attempted, it won't function as well as it does on Windows.
• Lack of Transparency: Because SSTP is proprietary, some users might be worried that it will be challenging to audit for security flaws. Third-party security researchers are not allowed to test or enhance the protocol.
• Performance: Although SSTP has good security, it might not be as quick as some other VPN protocols. This could have an impact on the pace at which data is sent, particularly when traveling great distances. In addition to using the TCP protocol, SSTP's sophisticated encryption can cause it to lag. This causes issues with peer-to-peer activities like gaming and streaming. In addition, compared to other VPN protocols, it takes more technical expertise and work to set up and operate.
• Dropping the Connection: Authenticated web proxies are incompatible with the SSTP protocol. only supports user authentication. This problem may restrict SSTP usage. Therefore, when the network administrator finds the header, the connection can be lost.
• TCP Meltdown: One technological problem with the TCP communication protocol is called TCP meltdown. Since SSTP makes use of TCP, it may have similar problems. The connection speed will become extremely sluggish after this. the cause of TCP's reduced speed compared to UDP.
• POODLE Attacks: There are speculations from recent times that indicate SSTP is vulnerable to POODLE attacks. This is because SSTP is based on SSL 3.0, which is well recognized for being vulnerable to POODLE attacks.

What is the Difference Between PPTP and SSTP?

SSTP is essentially a VPN extension that was developed to be more robust and secure than other VPN protocols. Because of its larger service area compared to PPTP, SSTP is more stable.

The primary drawback for SSTP users is its ownership by Microsoft, which results in a lack of transparency. This feature is limited to Windows devices, although it is readily integrated into any current version of the Windows operating system. Linux users do not have this advantage and normally pick PPTP if they only have the option between SSTP and PPTP.

With the help of SSTP, a potent VPN solution, users may safely and remotely access corporate networks. Therefore, it would seem that SSTP is the better VPN protocol when compared to PPTP. SSTP can penetrate almost any firewall and is more reliable and safe than PPTP.

PPTP has wider support than SSTP. The primary advantage of PPTP is its broad support. Any device that supports PPTP will be able to connect to the chosen VPN servers without any problems if you have to pick from a large selection of VPN providers. PPTP is a fast protocol since its inventors have had a lot of time to refine and streamline it due to its older age.

The ability of internet service providers or office managers to ban PPTP is its biggest drawback. On the other hand, SSTP makes use of port 443, which is the SSL/TLS port that web apps utilize. SSTP is usually not prohibited on any network, including a business network because it utilizes the same 443 port. Administrators don't have to worry about blocking SSTP VPN use on any network.

What is the Difference Between L2TP/IPsec and SSTP?

There are a number of factors to take into account when comparing SSTP to L2TP (Layer 2 Tunneling Protocol) and IPsec (Internet Protocol Security), including security, ease of setup, and compatibility.

Strong security is offered by both SSTP and L2TP/IPsec; however, there are configuration and platform support variations between the two. Because SSTP is engineered to function flawlessly with Windows operating systems, Windows-centric enterprises will find it to be an easy decision. On the other hand, L2TP/IPsec is more adaptable and works with a larger variety of hardware and operating systems, including mobile ones.

Both L2TP/IPsec and SSTP provide robust solutions for authentication and encryption. When deciding between the two, organizations should consider their unique demands and platform requirements.

While IPsec might be more difficult to implement than SSTP, it offers a strong security solution when used with L2TP. SSTP is simple to set up, particularly in Windows systems.

The decision between L2TP/IPsec and SSTP ultimately comes down to a number of variables, including platform variety, security needs, and implementation simplicity.

The following are the main distinctions between L2TP/IPSec and SSTP:

• Tunneling Protocols: SSTP tunneling protocol runs via HTTPS (HTTP Secure) and is based on the PPP (Point-to-Point Protocol). SSTP makes PPP traffic firewall-friendly by encapsulating it within SSL/TLS and facilitating its easy traversal of NAT (Network Address Translation) devices. L2TP is a tunneling protocol; it does not, by itself, offer encryption. For encryption and authentication, it is frequently used with IPSec. A second layer of security is provided by L2TP/IPSec, wherein L2TP establishes the tunnel and IPSec encrypts the data within.
• Transport Layer: SSTP functions at Layer 4, or the transport layer, in the OSI model. It is ideal for situations where SSL traffic is permitted since it leverages SSL/TLS for secure communication (e.g., across HTTPS ports). L2TP/IPSec functions at Layer 2 (data-link layer) and Layer 3 (network layer) of the OSI model. Layer 2 tunnel creation is done by L2TP, and Layer 3 encryption and authentication are done by IPSec.
• Use of Ports: SSTP usually uses TCP port 443, which is HTTPS traffic's standard port. Due to its use in safe online browsing, this port is frequently left open on firewalls. UDP ports 4500 are used for NAT traversal, and UDP ports 500 are used for the first key exchange (IKE) on L2TP/IPsec. L2TP itself makes use of UDP port 1701. Using numerous ports might present difficulties in particular network setups.
• Crossing a Firewall: Because SSTP uses the standard HTTPS port (443), it is made to easily get past firewalls and proxy servers. In situations where other VPN protocols could be restricted, this can be helpful. L2TP/IPSec may have issues in settings where certain IP or UDP protocol communication is prohibited. Another problem for firewall traversal may be the requirement for many ports.
• Compatibility of Platforms: SSTP was first created by Microsoft and is compatible with Windows-based devices and operating systems. Support for non-Windows systems is restricted. Numerous operating systems, including Windows, macOS, Linux, Android, and iOS, have extensive support for L2TP/IPSec. L2TP/IPSec becomes more adaptable in contexts with diverse networks as a result.

To summarize, the VPN protocols SSTP and L2TP/IPSec offer secure online communication. In Windows-centric contexts, SSTP is well-known for being firewall-friendly, while L2TP/IPSec offers more platform compatibility along with the extra protection of IPSec encryption. The decision between them is influenced by several elements, including platform specifications, firewall setups, and particular security requirements.

What is the Difference Between OpenVPN and SSTP?

SSTP is older than OpenVPN. In addition, OpenVPN is free and open source, with updates and evaluations from users. The industry standard for symmetric encryption, AES, is used.

SSTP is less secure than OpenVPN, which is the primary distinction between the two protocols. This is due to SSTP's usage of the SSL 3.0 protocol, which has been deprecated and is susceptible to the POODLE flaw. Conversely, OpenVPN makes use of the TLS protocol, which is unaffected by POODLE and is often more secure. Another distinction between OpenVPN and SSTP is that OpenVPN is cross-platform compatible, whereas SSTP is primarily designed for Windows and may be difficult to set up on other operating systems. It makes use of the OpenSSL library, which is widely used under Linux. The open-source library OpenSSL is to blame for the Heartbleed security flaw. OpenVPN, along with its OpenSSL library, is one of the safest options available on the market because of contributor code upgrades and reviews.

The encryption algorithm used by OpenVPN is AES, which is regarded as the industry standard for symmetric key encryption. Compared to the other two methods, it is far more dependable and is supported by most providers. The main drawback to the OpenVPN protocol is that setting up the environment requires greater technical know-how. Like SSTP, OpenVPN evades firewall constraints as well.

OpenVPN is more popular and widely acknowledged than SSTP, but customers who are not familiar with its settings find it too complicated to set up. Because SSTP is simple to set up and works well with Windows, it's frequently preferred over OpenVPN in Microsoft setups.

Examining the distinctions between SSTP and OpenVPN, as well as their relative benefits, is essential.

OpenVPN's advantages versus SSTP

• Because OpenVPN uses TLS rather than SSL, it is immune to POODLE attacks.
• OpenVPN is quicker since it can operate via UDP.
• Due to OpenVPN's great degree of customization, new options, including the use of extremely safe encryption methods like AES-256 are possible.
• Because OpenVPN is open source, its community of supporters continually inspects, maintains, and updates it.
• OpenVPN operates on all platforms; however, SSTP might not be compatible with devices that aren't Windows-based.

SSTP's advantages versus OpenVPN

• Because SSTP is a proprietary protocol created by Microsoft, it is more reliable and simpler to configure on Windows devices.
• By default, SSTP utilizes TCP port 443, which is the port that HTTPS traffic uses. This makes it more difficult for censoring software and firewalls to identify and ban.

How Secure is the SSTP Protocol?

One of the safest VPN protocols in terms of security is SSTP. SSTP adds an extra degree of security by utilizing the encryption and authentication mechanisms that are already present in Microsoft Windows.

Cryptographically speaking, SSTP is regarded as a secure protocol. It creates a secure connection between the client and the server using the AES and SSL/TLS encryption ciphers. By enclosing network communication in a secure SSL/TLS channel, SSTP guarantees network traffic security.

The SSTP standard was first implemented in Windows Vista and is still supported as a reliable secure protocol in Windows 7, 8, and 10. The native libraries of the Windows operating system make it easy to use and safe from side attacks and eavesdropping. Many companies that depend on encrypted communication between two places have opted to use it as a resource.

Even though the SSTP protocol suite includes SSL/TLS, you still need to take into account the cryptographic library and version that were used to encrypt the data. SSTP is a secure solution since it makes use of the AES (Advanced Encryption Standard) encryption algorithm. It makes use of the AES encryption algorithm, which is currently thought to be cryptographically safe, and 256-bit encryption. In spite of its potential for slowness, SSTP is nevertheless regarded as a fast protocol for encrypted and tunneled communications over AES-256.

How to Connect to an SSTP Server?

The following SSTP server connection procedures should be followed after obtaining SSTP VPN data (the IP address or hostname, username, and password) and making sure that Windows 7, Windows 8, and Windows 10, and Windows 11 are installed.

1. Access Network Settings: Click "Settings" > "Network & Internet settings" from the Start menu (the Windows symbol at the bottom left of the screen). To set up an SSTP VPN on Windows 11, go to Network Settings.
2. Add an SSTP VPN Connection: Click the "Add a VPN connection" button after selecting the "VPN" option from the left pane menu in the Network & Internet settings window. Establish a Windows SSTP VPN Connection
3. Set up SSTP VPN using the VPN server details: Set the "VPN Provider" box to "Windows (built-in)." Choose a name for your virtual private network. Enter the IP address or domain name of the SSTP VPN server in the "Server name or address" section. For "VPN type," choose "Secure Socket Tunneling Protocol (SSTP)." Select "Username and password" under "Type of sign-in info" for the authentication mechanism. In the slots for the username and password, enter the authentication details. To store your authentication details, check the "Remember my sign-in info" box. To save the VPN configuration, click "Save." Utilizing the VPN server information, configure Windows for SSTP VPN.
4. Set up the advanced feature: Find "Change adapter options" under "Related settings" when you return to the VPN menu. If you are unable to locate it, navigate to Network and Sharing Center > Control Panel. Modify the adapter's settings. Set up the VPN connection's advanced option on Windows. Use the drop-down menu to select "Properties" when you right-click on your VPN profile. To configure the VPN type to SSTP on Windows, click Properties. Choose "Secure Socket Tunneling Protocol (SSTP)" as the VPN type by navigating to the Security tab. Make sure "Allow these protocols" is on as well, then choose "OK." Verify the VPN's security settings on Windows.
5. Establish a Windows SSTP VPN connection: To establish a VPN connection, go to the VPN list, choose the recently added VPN profile, and press the "Connect" button. Open a Windows SSTP VPN connection.
6. Confirm Connection: After a connection is established, a successful connection is shown by the "Connected" status under the VPN profile and VPN icon in the system tray.

How to Create an SSTP VPN Connection in Windows 11?

Your VPN, whether at home or at work, includes SSTP. Get in touch with your system administrator or VPN service provider if you're not sure if it supports SSTP. To set up an SSTP VPN on a Windows 11 computer, follow these steps:

1. When using a Windows computer, select "Settings."
2. After selecting "Network and Internet," click "VPN."
3. Select "Add VPN," located in the upper right corner. choose "Add VPN."
4. After entering the information below, click "Save. Input your VPN information.
   • VPN service provider - integrated into Windows
   • Name of connection: My SSTP VPN;
   • Server name or address
   • Type of VPN: Secure Socket Tunneling Protocol (SSTP)
   • Type of login information: password and username
5. Select "Connect."

These are the standard instructions for setting up an SSTP VPN connection. Depending on your operating system and VPN provider, the instructions might change. Get in touch with your VPN provider's customer support or system administrator if you have trouble connecting to an SSTP VPN.

SSTP vs. PPTP vs. L2TP: Which is Best?

There are three older VPN protocols: PPTP, L2TP, and SSTP. Therefore, they don't really offer much in the way of security or privacy, despite being extensively supported across a variety of platforms. Your VPN service should, at the very least, be able to securely encrypt all data in transit, prevent tampering or "man-in-the-middle attacks," and authenticate your client and server with a dependable "handshake."

One kind of virtual private network (VPN) protocol that enables safe, distant web access is the Secure Socket Tunneling Protocol (SSTP). It is mostly used with Windows-based operating systems because it is a Microsoft product.

A secure connection between a client and a server is established using SSTP using the HTTPS protocol over TCP port 443. When utilizing HTTPS, most web proxies and firewalls may be circumvented.

Moreover, SSTP has SSL 3.0 encryption, which is more difficult to thwart than the L2TP and PPTP alternatives.

Because SSTP employs SSL/TLS encryption, it is regarded as more dependable and secure than PPTP and L2TP. Compared to SSTP and L2TP (Layer 2 Tunneling Protocol), PPTP (Point-to-Point Tunneling Protocol) is an older VPN protocol that is thought to be less secure. Compared to PPTP, L2TP is thought to be less secure than SSTP.