Virtual Private Networks once formed the backbone of secure remote connectivity. A single encrypted tunnel linked travelling employees to headquarters, and everything they needed, file shares, e-mail servers, intranet sites waited safely behind that fortress wall.
Today, the landscape is unrecognizable. Applications live in multiple clouds, workers split time between offices and home, and personal devices join the mix. Attackers exploit these changes by hijacking VPN credentials, moving laterally, and exfiltrating data through the same trusted tunnel defenders rely on.
Zero Trust Network Access (ZTNA) flips the model by starting from an assumption of breach and requiring proof of identity, device posture, and context before granting each micro-session. The pages that follow explain where VPNs excelled, where they now fail, and why granular, identity-aware access is rapidly becoming the gold standard.
A Refresher on VPN Technology
A Virtual Private Network creates an encrypted conduit using protocols such as IPSec or SSL between a client device and a termination gateway. Packets traverse public networks wrapped in cipher text, safeguarding them from eavesdroppers.
Once the tunnel is up, the client receives an internal IP address and functions as though it were inside the corporate LAN. Classic benefits include:
- Data Confidentiality – Strong encryption thwarts interception.
- Network Simplicity – One connection exposes every internal resource without extra configuration.
- Compatibility – Decades of support across operating systems and firewalls.
The same strengths produce weaknesses in modern settings. Because the client appears “inside,” it often gains broad reach file shares, printers, or databases irrelevant to the user’s task.
Security teams attempt network segmentation, but complex ACLs become brittle and error-prone. Monitoring north-south traffic at the gateway still leaves east-west movement invisible once malware breaches a workstation.
Zero Trust Network Access Explained
Organizations exploring secure remote access often ask, what is ZTNA in real-world terms? Simply put, it’s a service that checks each connection request on its own, gives just enough access to complete the task, and keeps verifying the user and device throughout the session.
Zero Trust is built on a clear principle: never trust, always verify. In a ZTNA setup, all resources are hidden behind an access broker that only responds to verified users and trusted devices.
The broker consults a policy engine checking identity attributes, device posture, location, and even time of day then opens a micro-tunnel to the specific application, not the entire network. If the session or device drifts out of compliance, the tunnel shuts automatically.
In practical terms, users launch a lightweight connector or browser-based session. They see only the applications expressly allowed by the role. Packet flow never exposes internal IP ranges, so adversaries cannot scan or lateral-hop.
Because access decisions occur in cloud points of presence, performance aligns with SaaS models rather than hair-pinning back to headquarters.
Comparing Core Attributes: ZTNA versus VPN
Access Granularity
- Legacy VPN: Grants full network access once the user logs in.
- ZTNA: Provides per-application access through micro-tunnels, limiting exposure.
Trust Model
- Legacy VPN: Trust is granted after authentication and remains throughout the session.
- ZTNA: Trust is never assumed verification continues throughout the session.
Client Architecture
- Legacy VPN: Typically requires heavier client software and split-tunnel configuration.
- ZTNA: Uses lightweight agents or browser-based access, often with cloud edge support.
Scalability
- Legacy VPN: Scaling depends on physical gateway appliance capacity.
- ZTNA: Cloud-native design allows automatic scaling with user demand.
Visibility
- Legacy VPN: Offers limited visibility into user activity once inside the network.
- ZTNA: Provides session-level logs with detailed user and device context for better oversight.
VPNs still provide value for narrow use cases like batch transfers to a legacy data center or highly regulated workloads requiring on-prem handshakes. Yet, for day-to-day SaaS and developer work, over-privileged tunnels create unnecessary risk.
Why Zero Trust Aligns With Future Requirements
Remote and Hybrid Work
Work-from-anywhere policies exploded during global lockdowns and remain popular. Employees log in from coffee shops using BYOD laptops. Rather than educating staff on when to launch VPN, admins configure a ZTNA client that silently enforces policy every time an app opens.
Identity-Based Security
Modern risk models treat credentials as one factor among many. ZTNA platforms integrate with identity providers, device-management tools, and security scores. A trusted laptop in corporate inventory may access code repositories; an unmanaged tablet receives only webmail.
Cloud-First Networks
Applications now sit in Azure, AWS, or Google Cloud. Backhauling traffic through a physical gateway adds latency and cost. Brokers deployed in those same clouds deliver localized access without exposing internal subnets.
Compliance and Audit
ZTNA logs pair each user action with device DNA, MFA state, and policy outcome. Auditors reviewing PCI activities or HIPAA ePHI transfers receive granular proof that only authorized roles touched protected data and only for the duration needed.
Choosing the Right Model: ZTNA or VPN or Both
Some scenarios still justify VPNs:
- A manufacturing plant uses proprietary protocols only routable within the factory LAN.
- A legal requirement mandates IPsec tunnels for a partner agency.
- Short-term contractors require temporary, bulk network access.
Elsewhere, migrating gradually to ZTNA eases change management:
- Deploy a broker for a single SaaS tool like Jira.
- Extend policies to internal web apps behind reverse proxies.
- Decommission unused VPN subnets once traffic shifts decisively.
Hybrid models blend the two: developers use ZTNA for code reviews and a split-tunnel VPN for server consoles residing on a private subnet awaiting modernization.
Selecting a Zero Trust Solution
Key evaluation factors:
- Identity Federation – Support for SAML, OIDC, and SCIM provisioning.
- Granular Policy Engine – Contextual checks like OS version, EDR status, and GPS location.
- Session Logging – Real-time analytics exportable to SIEM.
- Ease of Deployment – Agentless browser support, minimal changes to firewalls.
- Performance Footprint – Global points of presence minimizing latency to major SaaS regions.
Ask vendors how they handle certificate rotation, offline device caches, and emergency lockouts. Confirm they maintain continuous third-party pen testing and publish compliance attestations such as SOC 2 Type II.
Conclusion
VPNs solved the remote-access problem for a hub-and-spoke era. Today’s distributed, cloud-centric operating model demands per-session least privilege and continuous verification.
Zero Trust Network Access answers that call by shrinking attack surfaces, enhancing user experience, and scaling elastically with business needs. Organizations that evaluate access strategies now will mitigate risk and position themselves for the next wave of distributed work.
Frequently Asked Questions
Does ZTNA eliminate the need for network firewalls?
Network firewalls still protect east-west traffic among servers, but ZTNA minimizes exposure by ensuring that only authenticated sessions reach those internal zones.
What happens if the identity provider is unavailable?
Most brokers maintain token caches and device certificates to grant temporary access for a predefined grace period, then revalidate once the ID service returns.
Can legacy thick-client applications work with ZTNA?
Many solutions offer TCP forwarding or agent-based connectors that wrap non-web protocols in secure micro-tunnels, extending least-privilege principles even to older apps.