Zero Trust & Security Architecture: Design, Segment, Verify

Zero trust architecture is an enterprise design that removes trust based on network location. Every access request is decided per resource from verified identity, device state and context, follows a written policy, is limited in scope and time, and is logged. It is a set of principles applied through components, not a single product.

They are the logical components in NIST SP 800-207. The policy engine decides whether access is granted, denied or revoked. The policy administrator carries out that decision by opening or closing the path and issuing session credentials. The policy enforcement point sits in the data path and allows, monitors and ends connections.

A traditional VPN checks identity once at the edge and then grants network-level access, so a stolen credential can reach every system on the internal network. Zero trust network access instead publishes individual applications through a broker and decides each request using identity, device posture and context.

Usually with identity: one identity provider with single sign-on, phishing-resistant MFA starting with admins and partners, and no shared accounts. Then make device compliance a condition for client data, publish on-premises apps through ZTNA, segment the office LAN and log every decision.

It is a list with one row per access path: who may reach which resource, under which conditions, with which decision and session, enforced where and logged where. A final default-deny row refuses and logs anything not listed, which turns a list of permissions into a zero trust policy.

You cannot write least-privilege rules for flows you have never seen. Mapping connection records by role shows expected flows, surprising ones that need investigation and unknown devices. Segmenting without a flow map is the usual reason printers, scanners and backups break on the first day.