# Control entry to regulated maritime facilities at every MARSEC level > Use 33 CFR 105.255 -- Maritime Security: Facilities to review this narrow operational decision without extending the source beyond its stated scope. - Canonical URL: https://update.dsesecurity.com/updates/control-entry-to-regulated-maritime-facilities-at-every-marsec-level/ - Publisher: Detection Systems & Engineering (DSE Security) - Author: DSE Security Editorial Team - Published: 2026-08-27T12:11:10+00:00 - Modified: 2026-08-27T13:09:37+00:00 - Last reviewed by DSE: 2026-08-26 - Resource type: Briefing - DSE priority: Advisory - Topics: Access Control, Cybersecurity - Reading time: 3 minutes ## What you need to know Use 33 CFR 105.255 -- Maritime Security: Facilities to review this narrow operational decision without extending the source beyond its stated scope. ## Potentially affected Teams, systems, services, or facilities within the stated scope of 33 CFR 105.255 -- Maritime Security: Facilities ## DSE recommendation Compare the observed state with the cited official source, document applicability and exceptions, and test any approved change with rollback safeguards. ## Article Use this document to resolve one bounded operational decision: Control entry to regulated maritime facilities at every MARSEC level. Only the official source and traced locations below supply facts. Confirm applicability before acting. ## Source fact: The official [33 CFR 105.255 — Maritime Security: Facilities](https://www.ecfr.gov/current/title-33/section-105.255) from U.S. Coast Guard via eCFR supports the following bounded statements: - Under 33 CFR 105, a facility owner or operator must implement access-control measures that deter the unauthorized introduction of dangerous substances and devices, including devices intended to harm people, vessels, facilities, or ports. The research record locates this support at 33 CFR 105.255(a)(1), read with 33 CFR 105.255(a) (eCFR anchor p-105.255(a)(1)). - Under 33 CFR 105, MARSEC Level 1 measures must specify where access restrictions or prohibitions apply, including the points where TWIC access-control provisions will be used. The research record locates this support at 33 CFR 105.255(b)(1), read with 33 CFR 105.255(b) (eCFR anchor p-105.255(b)(1)). The source support ends with the statements listed above. Use them to examine credentials, readers, controllers, panels, door hardware, access decisions, monitoring, and life-safety interfaces in the applicable environment, not to imply a wider guarantee. ## What the source does not establish Applies only to facilities within 33 CFR part 105 and the cited section. Confirm Coast Guard jurisdiction, the approved Facility Security Plan, the current MARSEC level, and any approved alternatives; this is not legal advice or a universal facility-design standard. No current deployment state or change approval follows from the source alone. Validate identity sources, DNS where used, time, networks, power, fire systems, monitoring, and authorized operators, and treat examples or options as conditional inputs rather than defaults. ## Applicability questions - For source statement 1 at 33 CFR 105.255(a)(1), read with 33 CFR 105.255(a) (eCFR anchor p-105.255(a)(1)), which observable configuration, record, or test can confirm applicability here? - For source statement 2 at 33 CFR 105.255(b)(1), read with 33 CFR 105.255(b) (eCFR anchor p-105.255(b)(1)), which observable configuration, record, or test can confirm applicability here? - Which owner can attest to the recorded state of credentials, readers, controllers, panels, door hardware, access decisions, monitoring, and life-safety interfaces, including exceptions? - What baseline for identity sources, DNS where used, time, networks, power, fire systems, monitoring, and authorized operators must accompany the source-specific observation? - Which success, stop, and escalation criteria are written before testing begins? ## DSE recommendation: DSE recommends using the cited source as the evidence anchor for this decision. Make the source, asset scope, owner, and expected outcome explicit in the review record. Record the source location, examined part of credentials, readers, controllers, panels, door hardware, access decisions, monitoring, and life-safety interfaces, observed and expected states, owner, and reason for deviation. If the review warrants change, use a bounded implementation with prerequisites, test population, monitoring, abort criteria, and a rehearsed reversal. Sequence checks for identity sources, DNS where used, time, networks, power, fire systems, monitoring, and authorized operators and sanitize protected material before retention. ## Verification and evidence Build a reproducible chain from 33 CFR 105.255(a)(1), read with 33 CFR 105.255(a) (eCFR anchor p-105.255(a)(1)); 33 CFR 105.255(b)(1), read with 33 CFR 105.255(b) (eCFR anchor p-105.255(b)(1)) to the observed environment. Useful domain evidence includes approved configuration exports, access-event tests, controller state, door inspections, alarm handling, and exception records; label every item with scope, timestamp, collector, and stable identifier. Preserve both successful and failed observations, along with approval and rollback evidence. Avoid uncontrolled production experiments. Assign an expiry or event-driven recheck so the conclusion is not treated as permanent. ## Official references - [33 CFR 105.255 — Maritime Security: Facilities](https://www.ecfr.gov/current/title-33/section-105.255) — U.S. Coast Guard via eCFR ## Primary reference - Name: 33 CFR 105.255 -- Maritime Security: Facilities - Authority: www.ecfr.gov - URL: https://www.ecfr.gov/current/title-33/section-105.255 - Source publication date: Not stated by the source ## Citation and use Preferred citation: “Control entry to regulated maritime facilities at every MARSEC level,” DSE Security, https://update.dsesecurity.com/updates/control-entry-to-regulated-maritime-facilities-at-every-marsec-level/ Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/ Usage and citation policy: https://update.dsesecurity.com/usage/ Copyright © 2026 Detection Systems & Engineering. All rights reserved.