Today, employees access central enterprise applications from the home office and on the move. The applications themselves have long been distributed: partly in their own data center, partly in private clouds or as a SaaS service. Traditional remote access via VPN fits this reality ever more poorly, because it was designed for a world in which all important systems stood in one place.
Zero Trust Network Access (ZTNA) starts precisely here. The technology connects users specifically to individual applications, checks every access based on identity, device state, and context, and makes the internal network invisible to unauthorized parties. For IT decision-makers, ZTNA is therefore among the most important building blocks of a modern security architecture.
What is Zero Trust Network Access (ZTNA)?
Zero Trust Network Access refers to a security model for access to enterprise applications. Its basis is the Zero Trust principle: no user and no device is granted trust simply because both are located in a particular network. Every access request is checked and authorized individually. This applies to access from the home office just as much as to access from the office.
The decisive difference from older approaches lies in the level of access. ZTNA operates at the application level: an authorized user reaches exactly the applications for which a policy exists. The network behind it remains hidden from them. Systems that an attacker cannot see, they can neither scan nor deliberately attack.
In practice, ZTNA rarely appears in isolation. The technology is a core building block of SASE/SSE, an architectural model that provides network and security functions as a service from the cloud. Within it, ZTNA handles secure access to private applications. Further building blocks such as Secure Web Gateway and cloud access control secure access to the internet and SaaS services in parallel.
How does ZTNA work?
The technical heart is a broker, a brokering instance between users and applications. The broker receives every connection request, compares it against the stored policies, and only after a successful check establishes an encrypted tunnel to the target application. A direct network path between the end device and the corporate network is never created at any point.
Several factors feed into the access decision:
- Identity: Authentication runs through the company's central identity service, usually secured by multi-factor authentication.
- Device state: The broker checks whether the requesting device meets the requirements, for example regarding operating system version, encryption, and active endpoint protection.
- Context: Location, time of day, and the sensitivity of the target application also influence the decision.
The check does not end with the login. ZTNA continuously re-evaluates active sessions: if a device loses its compliance status during the session, access is restricted or terminated. On top of this comes a structural advantage in terms of reachability. The application environment builds the connection to the broker from the inside out, and inbound ports at the network edge are eliminated. As a result, private applications are simply not discoverable from the internet.
Why this matters
- A smaller attack surface: private applications remain invisible from the outside and offer attackers no direct point of entry. Exposed VPN gateways, a popular entry point, are eliminated entirely.
- Limited spread: stolen credentials or compromised devices open the way at most to individual applications. Lateral movement through the network, typical of ransomware attacks, is made considerably more difficult.
- Least privilege in practice: every user receives exactly the access their role requires. Permissions can be granted centrally and withdrawn just as quickly.
- A better user experience: access works identically from any location and without a detour via central dial-in points. This reduces latency and support effort.
- Traceability: every access is logged and can be attributed to a user, a device, and an application. This makes audits and the analysis of incidents easier.
Typical use cases
- Hybrid work: employees receive secure access to internal applications from the home office and on the move, with the same policies as in the office.
- External service providers: partners and maintenance technicians are given access to individual systems that is limited in time and function, without entering the corporate network.
- VPN replacement: companies replace overloaded or vulnerable VPN infrastructure step by step with application-specific access.
- Mergers and acquisitions: after a merger, users of the acquired organization can be connected quickly without coupling the networks of the two companies.
- Protecting critical systems: administrative access to sensitive servers or production systems is especially secured through additional context checks.
ZTNA vs. VPN
A VPN connects the end device to the corporate network. After dial-in, the user often moves largely freely within this network, because control takes place primarily at the entry point. From this arise the familiar problems: stolen credentials give attackers far-reaching access, and a vulnerability in the VPN gateway endangers the entire infrastructure behind it.
ZTNA reverses this model. Access applies per application, the check runs continuously, and the network itself remains hidden. On top of this comes better scaling: cloud-based ZTNA services grow with the number of users, whereas VPN concentrators become a bottleneck at peak times.
Another difference concerns the path of the data. VPN traffic often runs through central gateways, even when the target application is in the cloud. This creates detours and noticeable waiting times. ZTNA connects users directly to the respective application, regardless of where it is operated. In the transitional phase, many companies operate both approaches in parallel and move applications to ZTNA step by step.
ZTNA at KAEMI
KAEMI integrates ZTNA as a building block of modern SASE/SSE architectures , which unite access protection, web security, and network connectivity in a single operating model. In addition, Microsegmentation limits the spread of attacks within your infrastructure, so that Zero Trust is carried through consistently even behind the access point. If you are planning the switch from a VPN, our team supports you from analysis to ongoing operations: get in touch .