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        "title": "Validate TCP state transitions from handshake through close",
        "summary": "Use RFC 9293 — Transmission Control Protocol (TCP) to review this narrow operational decision without extending the source beyond its stated scope.",
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        "dse_recommendation": "Compare the observed state with the cited official source, document applicability and exceptions, and test any approved change with rollback safeguards.",
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        "content_html": "<p>Use this document to connect an official requirement or behavior to observable evidence: Validate TCP state transitions from handshake through close. Only the official source and traced locations below supply facts. Confirm applicability before acting.</p>\n<h2>Source fact:</h2>\n<p>The official <a href=\"https://www.rfc-editor.org/rfc/rfc9293.html\" target=\"_blank\" rel=\"noopener noreferrer\">RFC 9293 — Transmission Control Protocol (TCP)</a> from RFC Editor / Internet Engineering Task Force supports the following bounded statements:</p>\n<ul>\n<li>TCP establishes a connection through a three-way handshake, including simultaneous opens in which both peers transition through SYN-SENT and SYN-RECEIVED before ESTABLISHED. The research record locates this support at <strong>Section 3.5 (Establishing a Connection)</strong>.</li>\n<li>Data carried during connection synchronization cannot be delivered to the application until the receiver knows it is valid, such as after reaching ESTABLISHED. The research record locates this support at <strong>Section 3.5 (Establishing a Connection), data during synchronization</strong>.</li>\n<li>TCP closes its two directions independently, permits sending on the still-open half, and keeps an actively closed connection in TIME-WAIT for twice the maximum segment lifetime. The research record locates this support at <strong>Section 3.6.1 (Half-Closed Connections)</strong>.</li>\n</ul>\n<p>Do not import neighboring assumptions into the source record. The supported task is a scoped comparison involving address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains and the conditions the source actually describes.</p>\n<h2>What the source does not establish</h2>\n<p>This RFC evidence supports only the named network-protocol decision; it does not select vendor settings, topology, capacity, or an acceptable failure mode. A correct source interpretation can still be inapplicable to a particular design. Confirm DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring, ownership, and change authority instead of treating documented behavior as a deployment guarantee.</p>\n<h2>Applicability questions</h2>\n<ul>\n<li>For source statement 1 at <strong>Section 3.5 (Establishing a Connection)</strong>, which observable configuration, record, or test can confirm applicability here?</li>\n<li>For source statement 2 at <strong>Section 3.5 (Establishing a Connection), data during synchronization</strong>, which observable configuration, record, or test can confirm applicability here?</li>\n<li>For source statement 3 at <strong>Section 3.6.1 (Half-Closed Connections)</strong>, which observable configuration, record, or test can confirm applicability here?</li>\n<li>Within address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, which versions, roles, and configuration states define the review population?</li>\n<li>Could DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring invalidate the test, hide a failure, or change applicability?</li>\n<li>Who owns the decision, and which observation requires stopping, escalation, or rollback?</li>\n</ul>\n<h2>DSE recommendation:</h2>\n<p>DSE recommends using the cited source as the evidence anchor for this decision. Use a two-person review for the source interpretation and the resulting operational decision. Record the source location, examined part of address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, observed and expected states, owner, and reason for deviation.</p>\n<p>Translate the conclusion into change control only after documenting dependencies, impact, test method, expected signals, failure signals, and restoration steps. Include DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring, while excluding secrets and sensitive personal or topology data from ordinary tickets.</p>\n<h2>Verification and evidence</h2>\n<p>Tie each conclusion back to <strong>Section 3.5 (Establishing a Connection)</strong>; <strong>Section 3.5 (Establishing a Connection), data during synchronization</strong>; <strong>Section 3.6.1 (Half-Closed Connections)</strong> and to observable material such as configuration snapshots, route or neighbor state, packet captures, counters, topology records, and controlled failover results. Preserve provenance and stable identifiers without copying secrets into the evidence set.</p>\n<p>Retain the starting state, authorization, execution record, outcome, deviation, and final state as one review package. Move disruptive checks to an approved test path. Reopen the decision when versions, design, dependencies, ownership, or official guidance changes.</p>\n<h2>Official references</h2>\n<ul>\n<li><a href=\"https://www.rfc-editor.org/rfc/rfc9293.html\" target=\"_blank\" rel=\"noopener noreferrer\">RFC 9293 — Transmission Control Protocol (TCP)</a> — RFC Editor / Internet Engineering Task Force</li>\n</ul>",
        "content_text": "Use this document to connect an official requirement or behavior to observable evidence: Validate TCP state transitions from handshake through close. Only the official source and traced locations below supply facts. Confirm applicability before acting.\nSource fact:\nThe official RFC 9293 — Transmission Control Protocol (TCP) from RFC Editor / Internet Engineering Task Force supports the following bounded statements:\n\nTCP establishes a connection through a three-way handshake, including simultaneous opens in which both peers transition through SYN-SENT and SYN-RECEIVED before ESTABLISHED. The research record locates this support at Section 3.5 (Establishing a Connection).\nData carried during connection synchronization cannot be delivered to the application until the receiver knows it is valid, such as after reaching ESTABLISHED. The research record locates this support at Section 3.5 (Establishing a Connection), data during synchronization.\nTCP closes its two directions independently, permits sending on the still-open half, and keeps an actively closed connection in TIME-WAIT for twice the maximum segment lifetime. The research record locates this support at Section 3.6.1 (Half-Closed Connections).\n\nDo not import neighboring assumptions into the source record. The supported task is a scoped comparison involving address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains and the conditions the source actually describes.\nWhat the source does not establish\nThis RFC evidence supports only the named network-protocol decision; it does not select vendor settings, topology, capacity, or an acceptable failure mode. A correct source interpretation can still be inapplicable to a particular design. Confirm DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring, ownership, and change authority instead of treating documented behavior as a deployment guarantee.\nApplicability questions\n\nFor source statement 1 at Section 3.5 (Establishing a Connection), which observable configuration, record, or test can confirm applicability here?\nFor source statement 2 at Section 3.5 (Establishing a Connection), data during synchronization, which observable configuration, record, or test can confirm applicability here?\nFor source statement 3 at Section 3.6.1 (Half-Closed Connections), which observable configuration, record, or test can confirm applicability here?\nWithin address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, which versions, roles, and configuration states define the review population?\nCould DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring invalidate the test, hide a failure, or change applicability?\nWho owns the decision, and which observation requires stopping, escalation, or rollback?\n\nDSE recommendation:\nDSE recommends using the cited source as the evidence anchor for this decision. Use a two-person review for the source interpretation and the resulting operational decision. Record the source location, examined part of address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, observed and expected states, owner, and reason for deviation.\nTranslate the conclusion into change control only after documenting dependencies, impact, test method, expected signals, failure signals, and restoration steps. Include DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring, while excluding secrets and sensitive personal or topology data from ordinary tickets.\nVerification and evidence\nTie each conclusion back to Section 3.5 (Establishing a Connection); Section 3.5 (Establishing a Connection), data during synchronization; Section 3.6.1 (Half-Closed Connections) and to observable material such as configuration snapshots, route or neighbor state, packet captures, counters, topology records, and controlled failover results. Preserve provenance and stable identifiers without copying secrets into the evidence set.\nRetain the starting state, authorization, execution record, outcome, deviation, and final state as one review package. Move disruptive checks to an approved test path. Reopen the decision when versions, design, dependencies, ownership, or official guidance changes.\nOfficial references\n\nRFC 9293 — Transmission Control Protocol (TCP) — RFC Editor / Internet Engineering Task Force",
        "content_markdown": "Use this document to connect an official requirement or behavior to observable evidence: Validate TCP state transitions from handshake through close. Only the official source and traced locations below supply facts. Confirm applicability before acting.\n\n## Source fact:\n\nThe official [RFC 9293 — Transmission Control Protocol (TCP)](https://www.rfc-editor.org/rfc/rfc9293.html) from RFC Editor / Internet Engineering Task Force supports the following bounded statements:\n\n- TCP establishes a connection through a three-way handshake, including simultaneous opens in which both peers transition through SYN-SENT and SYN-RECEIVED before ESTABLISHED. The research record locates this support at Section 3.5 (Establishing a Connection).\n\n- Data carried during connection synchronization cannot be delivered to the application until the receiver knows it is valid, such as after reaching ESTABLISHED. The research record locates this support at Section 3.5 (Establishing a Connection), data during synchronization.\n\n- TCP closes its two directions independently, permits sending on the still-open half, and keeps an actively closed connection in TIME-WAIT for twice the maximum segment lifetime. The research record locates this support at Section 3.6.1 (Half-Closed Connections).\n\nDo not import neighboring assumptions into the source record. The supported task is a scoped comparison involving address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains and the conditions the source actually describes.\n\n## What the source does not establish\n\nThis RFC evidence supports only the named network-protocol decision; it does not select vendor settings, topology, capacity, or an acceptable failure mode. A correct source interpretation can still be inapplicable to a particular design. Confirm DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring, ownership, and change authority instead of treating documented behavior as a deployment guarantee.\n\n## Applicability questions\n\n- For source statement 1 at Section 3.5 (Establishing a Connection), which observable configuration, record, or test can confirm applicability here?\n\n- For source statement 2 at Section 3.5 (Establishing a Connection), data during synchronization, which observable configuration, record, or test can confirm applicability here?\n\n- For source statement 3 at Section 3.6.1 (Half-Closed Connections), which observable configuration, record, or test can confirm applicability here?\n\n- Within address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, which versions, roles, and configuration states define the review population?\n\n- Could DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring invalidate the test, hide a failure, or change applicability?\n\n- Who owns the decision, and which observation requires stopping, escalation, or rollback?\n\n## DSE recommendation:\n\nDSE recommends using the cited source as the evidence anchor for this decision. Use a two-person review for the source interpretation and the resulting operational decision. Record the source location, examined part of address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, observed and expected states, owner, and reason for deviation.\n\nTranslate the conclusion into change control only after documenting dependencies, impact, test method, expected signals, failure signals, and restoration steps. Include DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring, while excluding secrets and sensitive personal or topology data from ordinary tickets.\n\n## Verification and evidence\n\nTie each conclusion back to Section 3.5 (Establishing a Connection); Section 3.5 (Establishing a Connection), data during synchronization; Section 3.6.1 (Half-Closed Connections) and to observable material such as configuration snapshots, route or neighbor state, packet captures, counters, topology records, and controlled failover results. Preserve provenance and stable identifiers without copying secrets into the evidence set.\n\nRetain the starting state, authorization, execution record, outcome, deviation, and final state as one review package. Move disruptive checks to an approved test path. Reopen the decision when versions, design, dependencies, ownership, or official guidance changes.\n\n## Official references\n\n- [RFC 9293 — Transmission Control Protocol (TCP)](https://www.rfc-editor.org/rfc/rfc9293.html) — RFC Editor / Internet Engineering Task Force"
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                "description": "Use RFC 9293 — Transmission Control Protocol (TCP) to review this narrow operational decision without extending the source beyond its stated scope.",
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                "articleBody": "Use this document to connect an official requirement or behavior to observable evidence: Validate TCP state transitions from handshake through close. Only the official source and traced locations below supply facts. Confirm applicability before acting.\nSource fact:\nThe official RFC 9293 — Transmission Control Protocol (TCP) from RFC Editor / Internet Engineering Task Force supports the following bounded statements:\n\nTCP establishes a connection through a three-way handshake, including simultaneous opens in which both peers transition through SYN-SENT and SYN-RECEIVED before ESTABLISHED. The research record locates this support at Section 3.5 (Establishing a Connection).\nData carried during connection synchronization cannot be delivered to the application until the receiver knows it is valid, such as after reaching ESTABLISHED. The research record locates this support at Section 3.5 (Establishing a Connection), data during synchronization.\nTCP closes its two directions independently, permits sending on the still-open half, and keeps an actively closed connection in TIME-WAIT for twice the maximum segment lifetime. The research record locates this support at Section 3.6.1 (Half-Closed Connections).\n\nDo not import neighboring assumptions into the source record. The supported task is a scoped comparison involving address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains and the conditions the source actually describes.\nWhat the source does not establish\nThis RFC evidence supports only the named network-protocol decision; it does not select vendor settings, topology, capacity, or an acceptable failure mode. A correct source interpretation can still be inapplicable to a particular design. Confirm DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring, ownership, and change authority instead of treating documented behavior as a deployment guarantee.\nApplicability questions\n\nFor source statement 1 at Section 3.5 (Establishing a Connection), which observable configuration, record, or test can confirm applicability here?\nFor source statement 2 at Section 3.5 (Establishing a Connection), data during synchronization, which observable configuration, record, or test can confirm applicability here?\nFor source statement 3 at Section 3.6.1 (Half-Closed Connections), which observable configuration, record, or test can confirm applicability here?\nWithin address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, which versions, roles, and configuration states define the review population?\nCould DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring invalidate the test, hide a failure, or change applicability?\nWho owns the decision, and which observation requires stopping, escalation, or rollback?\n\nDSE recommendation:\nDSE recommends using the cited source as the evidence anchor for this decision. Use a two-person review for the source interpretation and the resulting operational decision. Record the source location, examined part of address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, observed and expected states, owner, and reason for deviation.\nTranslate the conclusion into change control only after documenting dependencies, impact, test method, expected signals, failure signals, and restoration steps. Include DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring, while excluding secrets and sensitive personal or topology data from ordinary tickets.\nVerification and evidence\nTie each conclusion back to Section 3.5 (Establishing a Connection); Section 3.5 (Establishing a Connection), data during synchronization; Section 3.6.1 (Half-Closed Connections) and to observable material such as configuration snapshots, route or neighbor state, packet captures, counters, topology records, and controlled failover results. Preserve provenance and stable identifiers without copying secrets into the evidence set.\nRetain the starting state, authorization, execution record, outcome, deviation, and final state as one review package. Move disruptive checks to an approved test path. Reopen the decision when versions, design, dependencies, ownership, or official guidance changes.\nOfficial references\n\nRFC 9293 — Transmission Control Protocol (TCP) — RFC Editor / Internet Engineering Task Force",
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