Rotate TCP-AO keys without breaking authenticated connection segments

Use this document to resolve one bounded operational decision: Rotate TCP-AO keys without breaking authenticated connection segments. Only the official source and traced locations below supply facts. Confirm applicability before acting.

Source fact:

The official RFC 5925 — The TCP Authentication Option from RFC Editor / Internet Engineering Task Force supports the following bounded statements:

• An individual Master Key Tuple cannot change during a connection, but implementations may add or remove tuples and switch which installed tuple the connection uses. The research record locates this support at Section 3.1 (Master Key Tuple), connection-lifetime rules.
• RNextKeyID announces the receive key an endpoint wants its peer to use; after authenticating a segment, a receiver switches its outgoing current key when that announced tuple is available. The research record locates this support at Sections 6.1 (Coordinating MKT Changes) and 7.5 (Receiving TCP Segments).
• Every TCP segment must be matched against applicable key tuples, and a segment whose TCP-AO authentication fails must be silently discarded. The research record locates this support at Section 7.3 (TCP Segments).

Keep the evidence boundary at these traced claims. They support a review of address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains; they do not support conclusions outside the source’s stated conditions.

What the source does not establish

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.

Applicability questions

• For source statement 1 at Section 3.1 (Master Key Tuple), connection-lifetime rules, which observable configuration, record, or test can confirm applicability here?
• For source statement 2 at Sections 6.1 (Coordinating MKT Changes) and 7.5 (Receiving TCP Segments), which observable configuration, record, or test can confirm applicability here?
• For source statement 3 at Section 7.3 (TCP Segments), which observable configuration, record, or test can confirm applicability here?
• Within address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains, which versions, roles, and configuration states define the review population?
• Could DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring invalidate the test, hide a failure, or change applicability?
• Who owns the decision, and which observation requires stopping, escalation, or rollback?

DSE recommendation:

DSE recommends using the cited source as the evidence anchor for this decision. Anchor the review in the cited section and keep observation separate from interpretation. 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.

Do not move from citation to production in one step. Pilot the decision where practical, observe agreed signals, retain a reversal point, and verify DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring. Handle credentials, keys, recovery data, and personal information through approved secure channels.

Verification and evidence

Keep the source locations Section 3.1 (Master Key Tuple), connection-lifetime rules; Sections 6.1 (Coordinating MKT Changes) and 7.5 (Receiving TCP Segments); Section 7.3 (TCP Segments) adjacent to the sanitized artifacts used for comparison. Prefer configuration snapshots, route or neighbor state, packet captures, counters, topology records, and controlled failover results, with enough identity and timing data for an independent recheck.

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.

Official references

• RFC 5925 — The TCP Authentication Option — RFC Editor / Internet Engineering Task Force