What is zero trust networking?

Zero Trust is a security model based on the principle "never trust, always verify" — no user, device, or network segment is trusted by default, even if inside the corporate perimeter. Traditional perimeter-based security assumes everything inside the firewall is safe — a single breach gives attackers free access to the internal network. Zero trust requires: strong identity verification (MFA, certificate-based) for every access request, device health validation (is the device patched? Has it been compromised?), least-privilege access (only access what is needed, nothing more), micro-segmentation (isolate workloads and restrict lateral movement), continuous monitoring and validation (re-verify throughout sessions). Implementation technologies: ZTNA (Zero Trust Network Access), SDP (Software Defined Perimeter), IAM, PAM, EDR, SIEM. NIST SP 800-207 defines the zero trust architecture. This approach is particularly relevant post-COVID with remote workers and cloud workloads outside traditional perimeters.