IPsec VPNs vs. SSL VPNs

IPsec and SSL/TLS function at different layers of the OSI model, but both can be used for VPNs. Learn the pros and cons of each.

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  • Network Layer
  • How the Internet Works
  • Routing
  • What is a LAN?
  • Internet Protocol (IP)
  • Glossary

IPsec vs SSL VPNs

Learning Objectives

After reading this article you will be able to:

  • Learn the differences between IPsec and SSL/TLS
  • Compare VPNs that use these protocols
  • Learn how VPNs are used for access control

What is IPsec?

IPsec helps keep private data secure when it is transmitted over a public network. More specifically, IPsec is a group of protocols that are used together to set up secure connections between devices at layer 3 of the OSI model (the network layer). IPsec accomplishes this by scrambling all messages so that only authorized parties can understand them — a process known as encryption. IPsec is often used to set up virtual private networks (VPNs).

A VPN is an Internet security service that allows users to access the Internet as though they were connected to a private network. VPNs encrypt Internet communications as well as providing a strong degree of anonymity. VPNs are often used to allow remote employees to securely access corporate data. Meanwhile, individual users may choose to use VPNs in order to protect their privacy.

What is SSL/TLS?

Secure Sockets Layer (SSL) is a protocol for encrypting HTTP traffic, such as connections between user devices and web servers. Websites that use SSL encryption have https:// in their URLs instead of http://. SSL was replaced several years ago by Transport Layer Security (TLS), but the term "SSL" is still in common use for referring to the protocol.

In addition to encrypting client-server communications in web browsing, SSL can also be used in VPNs.

IPsec VPNs vs. SSL VPNs: What are the differences?

OSI model layer

One of the major differences between SSL and IPsec is which layer of the OSI model each one belongs to. The OSI model is an abstract representation, broken into "layers," of the processes that make the Internet work.

The IPsec protocol suite operates at the network layer of the OSI model. It runs directly on top of IP (the Internet Protocol), which is responsible for routing data packets.

Meanwhile, SSL operates at the application layer of the OSI model. It encrypts HTTP traffic instead of directly encrypting IP packets.

Implementation

IPsec VPNs typically require installing VPN software on the computers of all users who will use the VPN. Users must log into and run this software in order to connect to the network and access their applications and data.

In contrast, all web browsers already support SSL (whereas most devices are not automatically configured to support IPsec VPNs). Users can connect to SSL VPNs through their browser instead of through a dedicated VPN software application, without much additional support from an IT team. (However, this means that non-browser Internet activity is not protected by the VPN.)

Access control

Access control is a security term for policies that restrict user access to information, tools, and software. Properly implemented access control ensures that only the right people can access sensitive internal data and the software applications for viewing and editing that data. VPNs are commonly used for access control, because no one outside the VPN can see data within the VPN.

Many large organizations need to set up different levels of access control — for instance, so that individual contributors do not have the same levels of access as executives. With IPsec VPNs, any user connected to the network is a full member of that network. They can see all data contained within the VPN. As a result, organizations that use IPsec VPNs need to set up and configure multiple VPNs to allow for different levels of access. And some users may need to log into more than one VPN in order to perform their jobs.

In contrast, SSL VPNs are easier to configure for individualized access control. IT teams can give users access on an application-by-application basis.

On-premise vs. cloud applications

Traditional on-premise applications run in an organization's internal infrastructure, such as an on-site data center. IPsec VPNs typically work best with these applications, as users access them via internal networks instead of over the public Internet, and IPsec functions at the network layer.

Cloud-based applications, also called SaaS (Software-as-a-Service) applications, are accessed over the public Internet and hosted remotely in the cloud. SSL VPNs integrate fairly easily with cloud-based applications but need additional configuration to work with on-premise applications.

What is Cloudflare's alternative to VPNs for access control?

Cloudflare Access enables organizations to control and secure access to internal applications without a VPN. Cloudflare Access puts applications behind Cloudflare's global network, helping both on-premise and cloud applications remain secure.