NordLayer - Network Security

What is SSL VPN? Its definition, types & comparison

While most long-distance exchanges nowadays happen over the internet, security wasn't something that was a consideration in its inception. Netscape Communications, an American computer services company, introduced Secure Sockets Layer (SSL) in 1995 to better secure sensitive data transfers over the internet.

This was a direct predecessor to the modern Transport Layer Security (TLS) encryption protocol. It was first introduced in 1999 as a direct upgrade to SSL. Even in its early development cycles, it was called SSL version 3.1. The name was changed to distance further away from the name associated with its company, Netscape. Therefore, nowadays, both SSL and TLS are used interchangeably.

As it's quite a tricky cybersecurity subject, so we wrote a short guide on everything you should know about SSL/TLS Virtual Private Network solutions and their application in the modern workplace.

SSL VPN types

All SSL Virtual Private Networks rely on TLS protocol. It's used for authentication when passing users to internal HTTP and HTTPS services via most modern web browsers or applications.

Generally, SSL VPNs can be classified into two major categories.

SSL portal VPN

SSL VPN portal enables a single connection to remote websites, much like any web page secured by HTTPS. An authenticated user is presented with a portal web page linking to various resources hosted on the organization's network.

This setup works best for resources that can be accessed via browser only. This may not be perfect if you need to run legacy applications or network services. To work around that, your network administrators must tinker around to make it possible.

SSL tunnel VPN

VPN tunnels don't have the same limitations as SSL portal VPNs extending beyond browser functionalities. The tunnel is an enclosed intermediary between the user's device and a VPN server. The gateway on the server becomes intermediary redirecting users to the organization's network services, websites, and other resources.

This setup requires secure tunneling and a client-side application that has to be set up. However, this method also means multiple simultaneous connections can be made, making it easier to take advantage of numerous web services.

Benefits and advantages of SSL VPN

SSL VPNs are mainly used to secure remote and network-level access between the client and the corporate network. Here are this technology's principal benefits.

Compatibility. One of the biggest appeals of SSL VPN setup is that it relies on standardized TLS protocols. All currently used browsers, like Chrome and Firefox, natively support TLS, which saves network administrators a lot of trouble setting up users' endpoints. As an additional benefit, browsers get frequent updates, which also frees up network administrators from having to oversee the process.

Easy maintenance. Unlike traditional VPN clients that require specific drivers and software installations, SSL VPNs rely on widely used web clients. This means that users don't have to install any additional software, and the solution works across a wide range of operating systems without additional effort. As for the updates and overall maintenance, as it's bundled with popular web browsers, the updates are automatically installed as soon as they're rolled out. Network administrators don't have to worry or manually push through their updates.

Highly customizable. SSL VPNs operate at the transport layer, making the traffic much easier to branch out. This makes it very easy to have secured tunnels to your internal company resources while keeping the public resources or applications less controlled.

Increases access security. SSL VPNs can only be configured to enable highly precise access rules building tunnels to specific applications. This means that users can't be allowed into the entire enterprise network, limiting the potential risks threatening the company. It ensures remote access but in such a way that it's not endangering the overall enterprise's security.

IPsec VPN vs. SSL VPN

IPsec VPN and SSL VPN comparison table
IPsec VPN and SSL VPN comparison table

Choosing between IPsec vs. SSL will be one of the important decisions for network administrators when implementing VPN. Both encryption types have their strengths and weaknesses, making them better in some use cases than others.

OSI model layer

Both protocol types belong to different OSI model layers — the framework describing the internet's basic functionality. For instance, the IPsec protocol works at the network layer of the OSI model. Meanwhile, SSL works at the application layer. This also means it encrypts HTTP traffic instead of directly encrypting IP packets.

Implementation

Due to their mode of operation, IPsec remote access requires installing VPN software on the device that will be used for secure connections. Depending on the software used, your organization may also need to provision software licenses and set up each user's endpoint. That's considerably more effort than SSL, which is natively supported by all web browsers.

Access control

One of the potential risks of IPsec VPNs is that any connected user is an equal member of that network. While it shrinks the enterprise as if you were directly on its premises, it poses significant security risks. For that reason, enterprises using IPsec need to provide different access privileges for different accounts, which can get tedious. In contrast, SSL VPNs can be easier to configure to allow individualized access policies. This allows specifying what and how it can be accessed.

On-premise vs. cloud applications

IPsec VPNs typically work best with traditional on-premise applications. The reason is that remote users access them via internal networks instead of the public internet, which makes it easier due to reliance on the network layer.

Meanwhile, cloud-based Software-as-a-Service applications are accessed only over the public internet. This method of connectivity makes it very easy to integrate with SSL VPNs. It makes them suitable for cloud-based applications, but there can be incompatibilities with on-premise applications.

Why SSL VPN technology is important?

As employees are more and more frequently accessing work environments remotely, secure remote access is one of the key priorities. This is where SSL VPNs come in, especially since more organizations are moving towards SaaS services instead of locally hosted resources.

SSL VPNs occupy a niche in the market that is easy to set up and use from any device without intricate setup methods. This makes the technology appealing to both organizations and remote users. When a globally distributed workforce has to be allowed to use a company's resources SSL VPNs' importance cannot be underestimated.

SSL VPN use-cases

Businesses and organizations use SSL VPN appliances for several functions. Here's how SSL VPNs are currently used in businesses.

Business continuity

SSL VPNs can be deployed dynamically to almost any device with internet access (provided it has a browser that supports SSL). For businesses who are looking into solutions that easily scale, SSL VPNs are near-perfect solutions. There's no need to install additional software on the end user's device (except for SSL certificates). SSL VPNs setups work right out of the box. This makes it easier to ensure smoother onboarding of remote users and provide them with critical resources.

An additional layer of authentication

Remote access usually involves risks as users join unmanaged networks (often unsupervised devices). Authentication is necessary to ensure that the remotely connecting person is who it claims to be. As SSL VPNs natively have authentication capabilities, introducing SSL often means adding authentication. SSL VPNs support expansions like RADIUS servers linked to cryptographic tokens provided by users in MFA systems.

Security health checks

SSL VPNs products can often perform security health checks on each inbound connection. Some can look for identification credentials, while others can search for specific software or certificates. This allows network administrators greater control over who can enter the organization's perimeter. Some additional precautions like jailbroken device detection can also be implemented to secure devices with compromised security systems.

Centralized access control

SSL VPNs provide granular controls over the organization's resources by providing centralized access controls. This means that network administrators can establish access rules with surgical precision. With such boundaries, data breaches aren't as threatening as a hacker's lateral movement is significantly restricted. In addition, access permissions can be easily revoked when the job roles are changed, so it's much easier to ensure the overall safety of the network ecosystem.

Summary

SSL VPN solutions are perfectly capable of protecting the confidentiality and integrity of online traffic. They are popular among businesses and users due to a very simple setup, as usually only a web browser is needed. The businesses appreciate their interoperability with cloud-based infrastructure and high level of security. As a cybersecurity solution, SSL VPNs aren't the most recent invention, but it's more than capable of giving an additional edge to your defenses.

In addition, SSL VPNs bring other benefits like authentication and security health checks. The protocol can be additionally enhanced to fit modern business needs. The biggest selling point is its capacity to provide an encrypted connection for each business case.