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MITRE D3FEND™ Learning Center

D3-NAM — Network Access Mediation

Network access mediation is the control method for authorizing access to a system by a user (or a process acting on behalf of a user) communicating through a network, including a local area network, a wide area network, and the Internet.

2Direct children
1Parent technique
1Related artifact
1Source reference

Isolate · D3FEND ontology 1.6.0 · Active

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Official D3FEND definition

Definition

Network access mediation is the control method for authorizing access to a system by a user (or a process acting on behalf of a user) communicating through a network, including a local area network, a wide area network, and the Internet.

Official D3FEND knowledge-base content

How it works

Network Access Mediation is a crucial process in telecommunications and IT networks that involves controlling access to network resources. It acts as an intermediary layer between network access requests and the actual network resources, ensuring that only authorized users and devices can access the network.

Bare Metal Cyber interpretation

Implementation perspective

Network Access Mediation should be treated as a technical defensive capability rather than a product checkbox. In practice, teams should define the protected scope, the conditions under which the technique acts, and the observable evidence that demonstrates the intended behavior. For this technique, likely engineering context includes the relevant system, activity, and evidence sources.

Use the technique to create a logical or physical boundary that limits access, execution, communication, or movement.

Questions to ask

  • What is being isolated, from whom or what, and under which conditions?
  • Which flows or operations remain explicitly allowed across the boundary?
  • What happens when the isolation mechanism fails or loses policy context?
  • How is the boundary tested for alternate paths, bypasses, and unintended dependencies?

Evidence and validation

  • Architecture and data-flow diagrams showing the isolation boundary
  • Policy, rule, or configuration exports from enforcing components
  • Tests of allowed, denied, and failure-state behavior
  • Monitoring evidence for boundary violations and policy changes

Common failure patterns

  • The intended boundary has undocumented alternate paths or inherited trust relationships.
  • Rules accumulate without ownership, review, or removal of obsolete exceptions.
  • Isolation is assumed from network location while application, identity, or management paths remain open.

This implementation perspective is original Bare Metal Cyber educational content. It does not replace the official D3FEND definition or establish that a specific product implements the technique.

Ontology hierarchy

Technique hierarchy

D3FEND graph relationships

Artifacts and ontology entities

These relationships describe how D3FEND connects a defensive technique to artifacts or other ontology entities. They describe graph semantics, not a product certification.

Explicit technique relationships

isolatesNetwork
Source record

Authoritative sources