Zero Trust Network Access: Identity-Centric Security Architecture

Part of the Cybersecurity Skills Guide — This article is one deep-dive in our complete guide series.

By HADESS Team | February 28, 2026 | Updated: February 28, 2026 | 5 min read

Zero Trust is not a product you buy. It is an architectural approach that removes implicit trust from your network. The traditional model of “inside the firewall is trusted, outside is untrusted” breaks down when users work from anywhere, applications run in multiple clouds, and attackers routinely gain internal network access through phishing or supply chain compromise.

Core Principles

Zero Trust operates on three principles:

Verify explicitly: every access request is authenticated and authorized based on all available data — user identity, device health, location, requested resource, and behavior patterns. A valid username and password alone is not sufficient.

Use least privilege access: grant the minimum access needed for the specific task. A developer accessing a staging database gets read access to that database, not VPN access to the entire staging network. Access is scoped to specific resources, not network segments.

Assume breach: design your architecture as if the attacker is already inside. Encrypt internal traffic. Monitor east-west communication, not just north-south. Implement detection that works within trusted zones, not just at the perimeter.

Identity-Based Access

In a Zero Trust model, identity replaces network location as the primary security control. Access decisions are based on:

• User identity: verified through strong authentication (MFA, phishing-resistant methods like FIDO2/WebAuthn)
• Device posture: is the device managed? Is the OS patched? Is EDR running and reporting clean? Is disk encryption enabled?
• Context: what time is it? What location? Is this a normal access pattern for this user? Is the request coming through a known VPN or directly?
• Resource sensitivity: accessing the company wiki has different requirements than accessing the customer database

Combine these signals in a policy engine that makes real-time access decisions. If a user’s device fails posture checks, they might get read-only access to low-sensitivity resources but be denied access to production systems until the device is remediated.

Microsegmentation

Network microsegmentation breaks the flat internal network into small, isolated zones. Instead of one big “corporate network” VLAN, each workload communicates only with the specific other workloads it needs.

Implementation approaches:

• Host-based firewalls: configure IPTables, Windows Firewall, or eBPF-based solutions on each host to enforce per-workload communication policies. Tools like Illumio and Guardicore manage host-based rules at scale.
• Network-based segmentation: use VLANs, VRFs, and firewall rules to create isolated segments. More traditional but harder to make granular.
• Service mesh: in containerized environments, service mesh solutions (Istio, Linkerd) provide mutual TLS between services and policy-based access control at the application layer.

Start microsegmentation by mapping application dependencies. You cannot write policies until you know which services talk to which other services. Run in monitor mode first to discover actual communication patterns, then build allow-list policies based on observed traffic.

Policy Engines

A Zero Trust architecture needs a policy decision point (PDP) that evaluates access requests against defined policies in real time. This is where identity signals, device posture, and context come together.

Commercial solutions include Zscaler Private Access, Cloudflare Access, and Google BeyondCorp Enterprise. Open-source options include the OpenZiti project and Pomerium.

Policy engines should support:

• Conditional access rules (if device is unmanaged, then require step-up authentication)
• Risk-based decisions (deny access if user risk score exceeds threshold)
• Session re-evaluation (continuously assess trust during the session, not just at login)
• Integration with your identity provider, EDR, and SIEM

Avoid building policy engines that only evaluate at connection time. A session that was safe when it started might become risky if the device’s EDR agent reports a detection mid-session. Continuous evaluation catches this.

Zero Trust architecture maps to Network Security Engineer and Security Architect career paths. Both roles need to design and implement identity-centric access models.

Zero Trust implementation experience

Related Guides in This Series

• EDR: Endpoint Detection, Response, and Threat Hunting — HADESS | 2026
• Firewall Management: Rules, Zones, and Change Control — HADESS | 2026
• Hardware Security Modules: Key Management and Compliance — HADESS | 2026

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