Translate TCP resets while preventing rejected traffic from refreshing NAT state

Use this document to connect an official requirement or behavior to observable evidence: Translate TCP resets while preventing rejected traffic from refreshing NAT state. Only the official source and traced locations below supply facts. Confirm applicability before acting.

Source fact:

The official RFC 7857 — Updates to Network Address Translation (NAT) Behavioral Requirements from RFC Editor / Internet Engineering Task Force supports the following bounded statements:

• A NAT must translate a TCP RST that matches an existing mapping and should retain the associated session state for four minutes unless another packet arrives. The research record locates this support at Section 2.2 (TCP RST).
• An inbound packet that matches endpoint-independent filtering but is rejected by security policy should not refresh the mapping, even when inbound refresh is enabled. The research record locates this support at Section 7 (Endpoint-Independent Filtering (EIF) Mapping Refresh).
• Outbound ICMP errors or TCP resets sent in response to inbound packets should not refresh the NAT mapping. The research record locates this support at Section 7.1 (Outbound Mapping Refresh and Error Packets).

The source support ends with the statements listed above. Use them to examine address plans, interfaces, routes, peers, protocol roles, timers, middleboxes, and intended failure domains in the applicable environment, not to imply a wider guarantee.

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 2.2 (TCP RST), which observable configuration, record, or test can confirm applicability here?
• For source statement 2 at Section 7 (Endpoint-Independent Filtering (EIF) Mapping Refresh), which observable configuration, record, or test can confirm applicability here?
• For source statement 3 at Section 7.1 (Outbound Mapping Refresh and Error Packets), 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. Make the source, asset scope, owner, and expected outcome explicit in the review record. 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.

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.

Verification and evidence

A reviewer should be able to retrace the decision from Section 2.2 (TCP RST); Section 7 (Endpoint-Independent Filtering (EIF) Mapping Refresh); Section 7.1 (Outbound Mapping Refresh and Error Packets) through configuration snapshots, route or neighbor state, packet captures, counters, topology records, and controlled failover results. Record what was collected, where, when, by whom, and which system or role it represents.

Keep before-state evidence, approval, test or change result, exceptions, and after-state evidence together. Use an approved lab, window, or nonproduction path for risky tests. Set a recheck trigger for version, architecture, dependency, vendor, incident, or ownership change. A check proves only what was observed.

Official references

• RFC 7857 — Updates to Network Address Translation (NAT) Behavioral Requirements — RFC Editor / Internet Engineering Task Force