Network Disconnect is the requirement that closes out network connections instead of leaving them open indefinitely. It sits in the System and Communications Protection (03.13) family, and it reduces the window an attacker has to hijack or reuse an idle session. Network Disconnect (03.13.09) requires terminating the network connection associated with a communications session at the end of the session or after a defined period of inactivity. Per the NIST discussion, this applies to internal and external networks, and terminating connections includes deallocating Transmission Control Protocol/Internet Protocol (TCP/IP) addresses or port pairs at the operating system level or deallocating networking assignments at the application level.
A common difficulty with this requirement is confusing this with session lock or user logout. This requirement is about the network connection itself timing out, not the user interface locking. Teams also miss that the timeout must fire both at the natural end of a session and after inactivity, and for Department of Defense (DoD) contractors the inactivity period is specified.
Where things stand for companies facing the transition from NIST 800-171 R2 to R3:
The following is reproduced verbatim from NIST 800-171 R3, requirement 03.13.09 Network Disconnect. Only the formatting has been adjusted for readability. This is a single statement with no lettered parts:
The source control is SC-10 from NIST 800-53. The bracketed assignment is the Organization-Defined Parameter (ODP): the inactivity time period. Per the NIST discussion, time periods of inactivity may be established by organizations and can include time periods by type of network access or for specific network accesses. You can read the requirement directly at NIST 800-171 R3, 03.13.09 (p. 60).
One (1) value sits inside this requirement. Depending on your contract, your organization may be permitted to define it. Organizations in the DIB subject to CMMC are not, because the DoD has defined it as policy.
The value below comes from Attachment A of the DoD Chief Information Officer (CIO) memorandum dated 10 April 2025 (signed David W. McKeown). The memo identifies each parameter by requirement sub-part, while NIST 800-171A R3 identifies the same parameter by ODP number. Both identifiers appear below so you can match your System Security Plan (SSP) language to either document.
The memo states that its values "will be updated as necessary," so confirm against the current version before writing them into policy.
NIST 800-171A R3 breaks 03.13.09 into two (2) assessment objectives: one (1) Organization-Defined Parameter (ODP) and one (1) determination statement. These AOs are:
The determination statement is that the connection terminates at the end of the session or after the defined inactivity period. If you are a DoD contractor, the ODP is specified. Per the DoD-specified ODP value in ComplianceForge's NIST 800-171 R3 Transition Guide, the inactivity time period (ODP[01]) is no longer than fifteen (15) minutes. The full guidance on assessment methods and objects, is in NIST 800-171A R3, 03.13.09 (p. 79).
Examine: system and communications protection policy and procedures; procedures for network disconnect; system design documentation; system configuration settings; system audit records; system security plan.
Interview: personnel with information security responsibilities; system developers; system administrators.
Test: mechanisms for supporting or implementing a network disconnect capability.
03.13.09 maps from NIST 800-171 R2 requirement 3.13.9 (terminate network connections associated with communications sessions at the end of the sessions or after a defined period of inactivity):
Mapped against the two (2) AOs, both (2) are direct (minimal effort), with no net-new AOs and none with no mapping. This is a clean carry-forward. If you satisfied R2 3.13.9, confirm the inactivity period aligns with the DoD-specified value of no longer than fifteen minutes for contract work.
Source Control in NIST 800-53 R5:
Secure Controls Framework (SCF) Crosswalk
Organizations running a single control set across multiple frameworks can satisfy 03.13.09 through the following SCF controls:
The crosswalks from NIST 800-171 R3 and NIST 800-171A R3 to the SCF are available at no cost through the SCF Set Theory Relationship Mapping (STRM): https://securecontrolsframework.com/start-here/set-theory-relationship-mapping-strm. The STRM also carries the relationship type for each mapping (Equal, Subset Of, Intersects With), which tells you whether an SCF control fully satisfies the requirement or only part of it. Mapping above taken from SCF 2026.3.
The following are issues teams may encounter rather than certainties. They are about the type of timeout and its triggers, each of which needs documented evidence of due diligence and due care such as policies, standards, procedures, and configuration screenshots:
Reasonable objective evidence for an assessment is often subjective. The following examples of evidence to address NIST 800-171 R3 03.13.09 are sourced from the SCF Evidence Request List (ERL), available at https://securecontrolsframework.com/free-content/scf-download. These ERL artifacts are mapped to NIST 800-171 R3 03.13.09 through SCF controls. They establish a starting point for discussions on what an organization needs to have for evidence of due diligence and due care to withstand external scrutiny by an assessor or regulator.
The SCF controls that carry this requirement have no dedicated ERL artifact, so evidence rests on the configuration and records that demonstrate the objectives directly.
Alongside these, keep the System Security Plan (SSP) narrative for 03.13.09 recording the ODP values you adopted.
With both AOs mapping directly, 03.13.09 is a light lift once the timeout is configured. A realistic sequence:
What value does the DoD require for the organization-defined parameter in NIST 800-171 R3 03.13.09? R3 leaves the value to the organization. For the DIB, the DoD set it in the 10 April 2025 memorandum under ODP identifier 03.13.09: no longer than 15 minutes.
How many assessment objectives does NIST 800-171 R3 03.13.09 have? NIST 800-171A R3 breaks 03.13.09 into two (2) assessment objectives: one (1) Organization-Defined Parameters (ODPs) and one (1) determination statements. An assessor works through each one separately, so each needs its own evidence.
Which NIST 800-53 R5 control does NIST 800-171 R3 03.13.09 come from? SC-10.
Where does NIST 800-171 R3 03.13.09 sit in the NIST 800-171 R3 Kill Chain? Phase 12, Secure Baseline Configurations (SBC). The Kill Chain is a phased model for sequencing R3 implementation, and it assigns this requirement to that phase.
03.13.09 Network Disconnect terminates the network connection associated with a communications session at the end of the session or after a defined period of inactivity. It maps directly from R2 3.13.9, so there is no net-new work. The recurring problem is confusing it with a screen lock or configuring only one trigger. Define the inactivity period (for DoD, no longer than fifteen minutes), terminate connections on both triggers, and apply it to internal and external access.
Authoritative sources:
Authoritative sources:
This guide reproduces U.S. Government text from NIST 800-171 R3 and NIST 800-171A R3 and references the DoD ODP memorandum of 10 April 2025. It is educational, not legal or assessment advice. Last reviewed: 2026-09-22.
