# NIST SP 800-171 Rev. 3 3.13.9 — Network Disconnect - Source: https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-13-9-network-disconnect - Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-171 Rev. 3 Requirements](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3) › System and Communications Protection — §3.13 - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **NIST SP 800-171 Rev. 3**·Requirement `3.13.9`·high·Component: **Situational Awareness** ## What this control requires > This control mandates terminating network connections associated with communications sessions either at the end of the session or after a defined period of inactivity. It includes deallocating network resources, such as TCP/IP addresses or port pairs, to ensure unused connections do not remain open. This control supports the Network Disconnect Management capability within the Situational Awareness (3.13) family. > > — NIST SP 800-171 Rev. 3, Requirement 3.13.9 ### In plain English This control mandates terminating network connections associated with communications sessions either at the end of the session or after a defined period of inactivity. In practice, this means you can prove you session management-level controls on a defined cadence. ## Why it matters DoD contractors and their subcontractors must implement all 100 SP 800-171 requirements to keep CUI handling contracts. Gaps are scored against the SPRS scoring methodology; below a 110-point starting score, each unmet requirement deducts points and a below-threshold score can disqualify a bid. This control is rated **high**. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation. ## What an auditor looks for A C3PAO conducting a CMMC Level 2 assessment uses NIST SP 800-171A objectives. They expect a System Security Plan (SSP), Plan of Action & Milestones (POA&M) for any gaps, and objective evidence (configurations, ticket records, training records) for every requirement. Within **Situational Awareness**, the assessor will trace your implementation back to the catalogue reference (Requirement 3.13.9) and look for objective evidence on the latest two assessment cycles. ## How to implement #### Cloud Posture **CSPM.** Run Wiz / Prisma / Defender for Cloud / Security Command Center over every account; auto-ticket findings above your accepted-risk threshold. #### Network Security **AWS.** VPC Flow Logs to S3, default-deny security groups, AWS Network Firewall for north-south, and Transit Gateway for hub-and-spoke segmentation. **Azure.** NSGs with deny-by-default, Azure Firewall Premium with TLS inspection, Private Endpoints for PaaS, and Microsoft Defender for Cloud's secure score for drift. **GCP.** VPC Service Controls perimeters around sensitive APIs, Cloud NGFW Enterprise for L7 inspection, Private Service Connect for managed services. #### Configuration Management **Policy-as-code.** Codify the control as Service Control Policies (AWS), Azure Policy initiatives, or Organisation Policy (GCP) so the platform enforces what the document promises. **IaC.** Gate Terraform / Pulumi / CloudFormation changes with Checkov / tfsec / OPA so misconfigurations never reach production. **Drift.** Run a CSPM (Wiz / Prisma / Defender for Cloud / Security Command Center) over every account and route findings to a single risk register. ### Operational checklist - **Session.** Document the trigger, the owner and the cadence. - **Configuration.** Document the trigger, the owner and the cadence. - **Security.** Document the trigger, the owner and the cadence. - **Network.** Document the trigger, the owner and the cadence. - **Scope:** management, inactivity, configuration, tcp, ip addresses, security, disconnect, port pairs. ## Evidence to collect - **Infra Scan.** Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings. Infrastructure posture tooling (AWS Config, Azure Policy, Nessus) verifies platform hardening. Focus: Network Disconnect. ## Common pitfalls - Treating CSPM findings as a backlog instead of a hot queue: findings older than the policy SLA accumulate until the auditor asks why. - Default-allow egress rules; East-West traffic with no segmentation; jump hosts on the public internet with password auth. - Manual cloud-console changes that never make it back to Terraform — drift accumulates until the next outage forces a reconciliation. ## How it maps to other frameworks Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit. - [**NIST SP 800-53 Rev. 5 SC-10** — Network Disconnect](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-10-network-disconnect) - [**ISO/IEC 27001:2022 A.8.22** — Segregation of networks](https://support.icompaas.com/compliance/iso-27001-2022/a-8-22-segregation-of-networks) - [**BSI C5:2020 COS-04** — Cross-network access](https://support.icompaas.com/compliance/bsi-c5-2020/cos-04-cross-network-access) - [**CIS Controls v8 13.4** — Perform Traffic Filtering Between Network Segments](https://support.icompaas.com/compliance/cis-controls-v8/13-4-perform-traffic-filtering-between-network-segments) ## Related controls in NIST SP 800-171 Rev. 3 - [**Requirement 3.13.6** — Network Communications - Deny by Default - Allow by Exception](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-13-6-network-communications-deny-by-default-allow-by-exception) - [**Requirement 3.4.6** — Least Functionality](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-4-6-least-functionality) - [**Requirement 3.13.8** — Transmission and Storage Confidentiality](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-13-8-transmission-and-storage-confidentiality) - [**Requirement 3.14.6** — System Monitoring](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-14-6-system-monitoring) - [**Requirement 3.14.8** — Information Management and Retention](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-14-8-information-management-and-retention) - [**Requirement 3.4.12** — System and Component Configuration for High-Risk Areas](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-4-12-system-and-component-configuration-for-high-risk-areas) ## References - [NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3](https://csrc.nist.gov/pubs/sp/800/171/r3/final) - Catalogue identifier: `Requirement 3.13.9` Topics: network securitycloud postureconfiguration management ## Related compliance guidance - [NIST SP 800-171 and CMMC: a practical guide to protecting CUI in the cloud](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3): Start with the full NIST SP 800-171 implementation guide — scope, roadmap, evidence and how the assessment runs. - [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): The catalogue 800-171 is tailored from, and the basis of the FedRAMP Moderate baseline your cloud providers must meet for CUI. - [ISO/IEC 27001:2022 compliance: a practical implementation guide](https://support.icompaas.com/compliance/iso-27001-2022): If commercial customers ask for a certificate as well, most 800-171 controls can be evidenced once and mapped to Annex A.