Keep this document to one review outcome: Drop source addresses that cannot legitimately arrive on an ingress interface. Only the official source and traced locations below supply facts. Confirm applicability before acting.
\nThe official RFC 2827 — Network Ingress Filtering: Defeating Denial of Service Attacks which employ IP Source Address Spoofing from RFC Editor / Internet Engineering Task Force supports the following bounded statements:
\nThe 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.
\nThis RFC evidence supports only the named network-protocol decision; it does not select vendor settings, topology, capacity, or an acceptable failure mode. Do not read the source as proof of implementation or permission to change production. Its guidance remains conditional on DNS, Active Directory authentication, PKI, time, routing policy, transport reachability, and monitoring and the environment’s recorded constraints.
\nDSE 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.
\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.
\nA reviewer should be able to retrace the decision from Sections 1 (Introduction) and 3 (Restricting forged traffic); Section 3 (Restricting forged traffic), dropped-packet logging; Section 4 (Further possible capabilities for networking equipment) 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.
\nKeep 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.
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