ZTNA vs VPN: How is Zero Trust Network Access revolutionizing secure remote access?

For more than two decades, the virtual private network (VPN) has been the gold standard and an undisputed synonym for secure remote access. Its operation could be compared to opening a fortified gate to a company’s castle. Upon successful authentication, a remote employee was granted access to the inner courtyard – the entire trusted corporate network – and could freely roam its resources. This model, based on the binary division of “trusted inside, untrusted outside,” worked well in a simpler, closed world. However, in today’s reality of hybrid work, cloud applications and distributed infrastructure, this philosophy has become not only outdated, but dangerous.

In response to these challenges, a revolutionary new concept was born: Zero Trust Network Access (ZTNA). ZTNA rejects the idea of opening the entire gateway. Instead, it works like a system of individual, guarded doors leading to each individual room (application) in the lock. Every time a user wants to enter a particular room, the guard (the ZTNA system) meticulously verifies the user’s identity and credentials, regardless of whether the user is already inside the lock or not. This is a fundamental paradigm shift that moves security from the network level to the application and identity level, fitting perfectly with the realities of today’s distributed work world.

How does a traditional VPN work and why has it been the standard for remote access over the years?

VPN (Virtual Private Network) is a technology that creates a secure, encrypted communications “tunnel” over a public network, such as the Internet. This allows a remote user to connect to the corporate network as if their computer were physically connected to an office outlet. All communication is encrypted, protecting it from eavesdropping and manipulation by potential attackers on the public network.

For years, VPN was the standard because it perfectly suited the needs of a “castle and moat” architecture. When most of a company’s resources (file servers, databases, ERP systems) were located in a central corporate data center, a VPN was a logical and effective way to “pull” a remote employee into a secure, trusted network perimeter. Once successfully connected and authenticated, the user’s device was given an internal IP address and became a de facto part of the LAN, gaining broad access to its resources.

The model was based on a simple philosophy: connect, then authenticate. The user first established a connection to the VPN hub at the network edge, and only then verified his identity. Most importantly, after a successful connection, he would gain access to the entire network by default, and any restrictions had to be implemented downstream, such as through access control lists (ACLs) on firewalls or routers.

What are the fundamental disadvantages and security risks associated with VPN architecture?

The VPN operating model, while effective for its era, generates several fundamental security risks in today’s threat landscape.

Huge attack surface: A traditional VPN, while granting access to the entire network, works on an all-or-nothing basis. If an attacker manages to take over an employee’s VPN credentials (e.g., through phishing), he gains an open path to the entire internal infrastructure of the company. He gains an “inside the walls” position from which he can freely scan the network, look for vulnerabilities and conduct lateral movement (lateral movement) to get to the most valuable resources. The VPN becomes a wide-open gateway for the intruder in this scenario.

Over-privileged access: A user who only needs access to one specific application is given access to hundreds of other systems via VPN that he doesn’t need for his work. This is a clear violation of the principle of least privilege and unnecessarily increases risk.

Poor performance and user frustration: In the cloud era, the VPN model is becoming a bottleneck. Traffic from a remote employee to a SaaS application (e.g., Microsoft 365) must first go to the company’s data center through a VPN tunnel, and only from there to the Internet. This inefficient route (known as “hairpinning” or “tromboning”) generates high latency and spoils the user experience, prompting users to find ways to bypass the VPN (known as “split tunneling”), creating further security vulnerabilities.

What is ZTNA (Zero Trust Network Access) and what philosophy is it based on?

ZTNA (Zero Trust Network Access) is a modern secure access solution that embodies the Zero Trust philosophy (“never trust, always verify”). The basic premise of ZTNA is that no user or device can be trusted by default, whether it is inside or outside the corporate network. Any attempt to access a resource must be treated as potentially hostile and subjected to rigorous verification.

ZTNA completely reverses the VPN operating model. Instead of the “connect to the network, then verify” philosophy, it uses the “verify, then connect to the application” principle. The user is never allowed “into the network.” Instead, after successful and continuous verification, the system creates a secure, encrypted 1-to-1 micro-tunnel for him, leading only to the one specific application he has requested access to.

Crucially, ZTNA-protected applications are invisible to the public Internet (and to unauthorized users). They are hidden behind a so-called ZTNA connector or broker, which is the only access point. An attacker, scanning the network, simply does not “see” the application servers, which drastically reduces the attack surface.

What is the key difference: network access (VPN) vs application access (ZTNA)?

The most important conceptual difference to understand is the paradigm shift from network-based access to identity- and application-based access.

VPN thinks in terms of networks. Its job is to “move” a user’s device to a trusted network segment. Once that task is done, its role ends. What a user can do inside that network is controlled (or not) by other mechanisms, such as firewalls or access control lists. A VPN is like a drawbridge – once lowered, anyone with a pass can enter the castle courtyard.

ZTNA thinks in terms of applications and identity. It’s not interested in “getting on the network.” It is interested in granting a specific, verified user, using a secure, verified device, access to one specific application. ZTNA creates a logical access boundary around each individual application, not around the entire network. It’s as if each room in a castle has its own guard and a separate magic door that appears only to authorized individuals.

This change in perspective has huge security implications. Even if an attacker seizes the credentials and device of an authorized employee, he will only gain access to those few applications to which that employee had explicitly assigned permissions. All the rest of the infrastructure will remain invisible and inaccessible to him, effectively blocking the attack from spreading.

How does ZTNA improve the convenience and efficiency of remote working compared to VPNs?

In addition to tremendous security benefits, ZTNA also offers significant improvements in productivity and user experience, which is key to keeping distributed teams productive.

In the VPN model, user traffic to a cloud application must first travel a long distance to the company’s data center, which introduces significant latency. In the ZTNA model, especially when integrated with a SASE architecture, the connection is set up optimally. The user connects to the service provider’s geographically closest point of presence (PoP), where his or her identity is verified, and then traffic is routed via the shortest, fastest route directly to the target application, whether in a public cloud or private data center. This eliminates latency and ensures smooth application performance.

Moreover, for the user, ZTNA is often completely transparent. He does not have to remember to manually start and stop the VPN client. Access to the application runs in the background, seamlessly and automatically. The employee simply clicks on the application icon on his desktop (be it a web application or an internal system), and ZTNA does all the magic in the background to verify and create a secure connection. This eliminates the frustration of slow and cumbersome traditional VPN clients.

How can nFlo help your company securely transform remote access?

Migrating from a traditional VPN architecture to a modern ZTNA model is a strategic project with huge benefits, but it requires careful planning and deep expertise. At nFlo, we act as a partner in this transition, helping organizations make a secure and smooth transition to the future of remote access.

Our approach begins with a consulting and strategic phase. Together with the client, we analyze their current remote access environment, identify key applications and user groups, and map data flows. Based on this, we help build the business case and roadmap for migration to ZTNA, selecting the deployment model (e.g., as part of a broader SASE strategy or as a standalone solution) that best fits the organization’s needs and maturity.

We specialize in the design, implementation and integration of market-leading ZTNA solutions. Our team of certified engineers handles the entire technical process – from integration with an existing identity provider (e.g., Azure AD, Okta), to configuration of granular access policies for individual applications, to deployment of connectors in the customer’s environment. We ensure a smooth transition for end users, often deploying both solutions in parallel during the transition phase. We also offer managed services, where our SOC team monitors and manages the ZTNA platform on an ongoing basis, ensuring the highest level of security and availability.