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In Security Last updated: July 10, 2023
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Are you looking for a more comprehensive network security solution? Let’s understand the difference between VPN, SDP, and ZTNA.

VPNs (Virtual Private Networks) have been helping businesses with secure access for linking branches, remote workers, and third parties for more than 25 years. However, network and communication requirements are continually evolving, and sophisticated cybersecurity threats are becoming more common.

What’s more, research shows that 55 percent of companies now have workers who are often remote, 50 percent of company data is stored on the cloud, and dangers are just as likely to be inside the perimeter as outside. As a result, VPNs are beginning to show their age because they do not adequately address the security concerns in the new landscape.

Your current VPN provider may be unable to modernize its technology to adapt to the security threats we face today. This is where Software Defined Perimeters (SDP) and Zero Trust Networks Access (ZTNA) come in. These are similar approaches to VPNs but more innovative, strict, and comprehensive network security solutions.

What are VPN, SDP, and ZTNA?

Let’s understand them!

Virtual Private Networks (VPNs)

VPN refers to a network connection based on virtual secure tunnels between points that protect users on public networks. VPNs authenticate users from outside the network before tunneling them inside. Only users logged into the VPN can see and access assets and gain visibility into the network activity.

Suppose you are using a VPN to browse the internet. In that case, your ISP (Internet Service Provider) and other third parties will not be able to monitor which websites you visit or the data you transmit and receive because the VPN server becomes the source of your data. It encrypts your internet traffic and hides your online identity in real-time. Likewise, cybercriminals can not hijack your internet traffic to steal your personal information.

However, VPNs have several drawbacks. For instance, cloud computing and Software-as-a-Service (SaaS) was not used when the legacy VPN was invented. When VPNs were developed, most companies stored their data on internal corporate networks. And remote employment was uncommon in this era.

Disadvantages of VPN

Here are some disadvantages of VPNs that make them insecure and inconvenient for organizations today:

Open ports: VPN concentrators (the networking equipment that provides the VPN connections) rely on open ports to establish VPN connections. The problem is cybercriminals often target open ports and use them to gain access to networks.

Access at the network level: Once a VPN authenticates users and lets them inside the network, they have unrestricted access, which exposes the network to threats. This design flaw leaves the data, applications, and intellectual property of a company vulnerable to attacks.

Inadequate authorization: Unlike SDP and ZTNA, VPNs do not require identification for both users and devices who are trying to access a network. And with users always having poor password practices and not to mention the millions of stolen user credentials available for sale on the dark web, hackers can capture and bypass two-factor authentication codes on your online accounts.

Vulnerabilities in software: Many popular VPN systems have been discovered to contain software problems that fraudsters have been able to exploit over time. Cybercriminals scan for unpatched VPN software because it leaves enterprises vulnerable to attack. This is true for VPN users who have not updated their software even when vendors offer patches promptly.

Ineffective performance: VPN concentrators can cause choke points, resulting in slow performance, cause excessive latency, and overall bad experience for the user.

Inconvenient: Setting up VPNs is an expensive and time-consuming procedure requiring a lot of effort from the security team and users. In addition, VPNs are not a secure network security solution because of the typical technological vulnerabilities that increase the attack surface.

Software-Defined Perimeter (SDP)

SDP, also referred to as a “Black Cloud,” is a computer security approach that conceals Internet-connected infrastructure such as servers, routers, and other company assets from being seen by outside parties and attackers, whether on-premises or in the cloud.

SDP controls access to organizations’ network resources based on an identity authentication approach. SDPs authenticate both device and user identities by first assessing the state of the device and verifying the user’s identity. An authenticated user is given their encrypted network connection, which no other user or server can access. This network also includes only those services that the user has been granted access to.

This means that only authorized users can see and access the firm’s assets from the outside, but no one else can. This distinguishes SDP from VPNs, which impose restrictions on user privileges while allowing unrestricted network access.

Zero Trust Network Access (ZTNA)

ZTNA security solution enables secure remote access to applications and services based on access control regulations.

In other words, ZTNA trusts no user or device and restricts access to network resources even if the user has accessed those same resources previously.

ZTNA ensures that every person and managed device attempting to access resources on a zero-trust network undergoes a tight identity verification and authentication process, whether they are inside or outside the network perimeter.

Once ZTNA has established access and validated the user, the system grants the user access to the application over a secure, encrypted channel. This adds an extra layer of security to corporate apps and services by hiding IP addresses that would otherwise be exposed to the public.

One of the leaders in the ZTNA solution is Perimeter 81.

YouTube video


SDPs are more secure because, unlike VPNs, which allow all connected users to access the entire network, SDPs enable users to have their private network connection. Users can only access company assets allocated to them.

SDPs may also be more manageable than VPNs, particularly if internal users require several levels of access. Using VPNs to manage several levels of network access necessitates the deployment of numerous VPN clients. With SPD, there’s no one client that everyone who uses the same resources connects to; instead, each user has their network connection. It’s almost as if everyone had their own personal virtual private network (VPN).

Furthermore, SDPs validate both devices and users before accessing the network, making it significantly more difficult for an attacker to gain access to the system using only stolen credentials.

SDPs and VPNs are distinguished by a few other essential characteristics:

  • SDPs are unconstrained by geography or infrastructure. This means SPD can be used to secure both on-premises infrastructure and cloud infrastructure because they are software-based rather than hardware-based.
  • Multi-cloud and hybrid cloud installations are also easily integrated with SDPs.
  • SDPs can connect users from anywhere; they don’t have to be within a company’s physical network boundary. This means SDPs are more helpful in managing remote teams.


Unlike VPNs, which trust every user and device inside the network and provide full access to the LAN (Local Area Network), a Zero Trust design works on the principle that no user, computer, or network, inside or outside the perimeter, can be trusted– by default.

Zero Trust security ensures that everyone attempting to acquire access to network resources is verified and that the user has access to only those services that have been explicitly authorized to them. ZTNA examines the device’s posture, authentication state, and user location to ensure pre-authentication trust.

This solves a typical VPN problem in which BYOD (bring your own device) remote users are given the same degree of access as users in a corporate office, although they often have fewer security restrictions.

Another difference is that although a classic VPN network security can prevent access from outside the network, they are designed to trust users inside the network by default. They grant users access to all network assets. The issue with this strategy is that once an attacker gains access to the network, they have complete control over everything inside.

A zero-trust network also allows security teams to set location or device-specific access control policies to prevent unpatched or vulnerable devices from connecting to the company’s network services.

To summarize, ZTNA has many advantages over VPN:

  • More secure – ZTNA creates an invisibility cloak around users and applications.
  • Only allocated cloud-based and internal server-based company resources are available to both remote workers and onsite users.
  • More straightforward to handle – ZTNA is built from the bottom up for today’s network security landscape, with excellent performance and easy integration in mind.
  • Better performance — cloud-based ZTNA solutions ensure adequate authentication of both the user and the device, removing the security problems that VPNs create.
  • Scalability is more effortless – ZTNA is a cloud-based platform that is easy to scale and does not require any equipment.


SDP (Software Defined Perimeters) and ZTNA (Zero Trust Networks Access) both employ the concept of a dark cloud to keep unauthorized users and devices from viewing applications and services they don’t have access to.

ZTNA and SDP only allow users access to the specific resources they need, which significantly reduces the risk of lateral movement that would otherwise be possible with VPNs, especially if a compromised endpoint or credentials allowed scanning and pivoting to other services.

SDPs employ a zero-trust architecture by default, which means that access is withheld unless a user can satisfactorily authenticate their identity.

Integrating your current VPN with SDP and ZTNA

VPNs are still the most popular cloud access security technology, according to a recent NetMotion survey of 750 IT executives. More than 54 percent of companies used VPNs to provide secure remote access in 2020, compared to 15 percent who used ZTNA and SDP solutions.

Graph showing how organizations use VPN vs. SDP vs. ZTNA

Another survey conducted by the company shows that 45 percent of businesses plan to use VPNs for at least another three years.

But to create a more comprehensive and secure network connection between users and devices, you can incorporate SDP and ZTNA with your current VPN. Using these security solution tools, it can be very easy for the security team to customize and automate access based on an employee’s roles and needs within the organization.

And access to sensitive data and apps can be kept safe while remaining seamless and unobtrusive, regardless of whether employees are on-premises or in the cloud.

Final words 👨‍🏫

As a network, IT, and security teams collaborate to minimize the attack service and prevent threats in their organizations, many may discover that investing in an SDP or ZTNA solution and incorporating it with their current VPN is the most logical solution.

They will also discover that these security changes don’t have to be rapid, disruptive, or expensive. But they can and should be pretty effective.

  • Mary Manzi
    I am a hubspot certified cybersecurity content writer. I have also been featured on a health and wellness site. I also publish cybersecurity news related articles on my LinkedIn pulse. I am currently working with cyber security… read more
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