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Network Access Control (NAC) is a computer networking solution that uses a set of protocols to define and implement a policy that describes how to secure access to network nodes by devices when they initially attempt to access the network. NAC might integrate the automatic remediation process (fixing non-compliant nodes before allowing access) into the network systems, allowing the network infrastructure such as routers, switches and firewalls to work together with back office servers and end user computing equipment to ensure the information system is operating securely before interoperability is allowed. A basic form of NAC is the 802.1X standard.
Network Access Control aims to do exactly what the name implies—control access to a network with policies, including pre-admission endpoint security policy checks and post-admission controls over where users and devices can go on a network and what they can do.
When a computer connects to a computer network, it is not permitted to access anything unless it complies with a business defined policy; including anti-virus protection level, system update level and configuration. While the computer is being checked by a pre-installed software agent, it can only access resources that can remediate (resolve or update) any issues. Once the policy is met, the computer is able to access network resources and the Internet, within the policies defined within the NAC system. NAC is mainly used for endpoint health checks, but it is often tied to Role based Access. Access to the network will be given according to profile of the person and the results of a posture/health check. For example, in an enterprise, the HR department could access only HR department files if both the role and the endpoint meets anti-virus minimums.
Goals of NAC
Because NAC represents an emerging category of security products, its definition is both evolving and controversial. The overarching goals of the concept can be distilled to:
Mitigation of non-zero-day attacks
The main benefit of NAC solutions is to prevent end-stations that lack antivirus, patches, or host intrusion prevention software from accessing the network and placing other computers at risk of cross-contamination of computer worms.
NAC solutions allow network operators to define policies, such as the types of computers or roles of users allowed to access areas of the network, and enforce them in switches, routers, and network middleboxes.
Identity and access management
Where conventional IP networks enforce access policies in terms of IP addresses, NAC environments attempt to do so based on authenticated user identities, at least for user end-stations such as laptops and desktop computers.