# What is Network Access Control (NAC)?

> Network access control (NAC) is a policy and enforcement capability that governs which users and devices may connect to a network and what network access they receive.

- Canonical URL: https://yellowcube.eu/glossary/network-access-control/
- Publisher: Yellow Cube
- Language: en
- Contact: hello@yellowcube.eu

## Content

It can evaluate identity, device ownership, security posture, location, connection method, and other context before admission and while a connection remains active.

A NAC design usually coordinates identity and device information with enforcement points such as switches, wireless infrastructure, remote-access gateways, or firewalls. Depending on policy, an endpoint may receive normal access, a restricted segment, remediation access, guest access, or no connection.

### Key points

- **Identification and authentication:** Use mechanisms such as IEEE 802.1X and certificates where supported, while profiling or registering devices that cannot participate in strong authentication.
- **Context assessment:** Consider device management state, supported software, protection status, known risk, user role, location, and requested access.
- **Policy enforcement:** Apply network permissions through controlled ports, access rules, segmentation assignments, or quarantine and remediation paths.
- **Operational design:** Plan onboarding, certificate lifecycle, guest and contractor access, unmanaged and OT devices, logging, exceptions, and fail-open or fail-closed behavior.
- **Important limitation:** A posture check is a point-in-time assessment, and weak identifiers such as a MAC address can be copied. Admission should not create permanent trust or unrestricted reachability.

### Related terms

[IEEE 802.1X authentication](<https://yellowcube.eu/glossary/ieee-802-1x-authentication/>) · [Network segmentation](<https://yellowcube.eu/glossary/network-segmentation/>) · [Zero trust architecture (ZTA)](<https://yellowcube.eu/glossary/zero-trust-architecture/>) · [Conditional access](<https://yellowcube.eu/glossary/conditional-access/>)

### Sources

[NIST glossary: Network Access Control](https://csrc.nist.gov/glossary/term/network_access_control) · [IEEE 802.1X-2020: Port-Based Network Access Control](https://standards.ieee.org/ieee/802.1X/7345/) · [NIST SP 800-207: Zero Trust Architecture](https://csrc.nist.gov/pubs/sp/800/207/final)

## Attribution and scope

This Markdown representation is generated from the same approved content records as the canonical HTML page. Cite the canonical URL above when referencing this material. Product and service descriptions are informational; confirm project-specific requirements with Yellow Cube.