# Generate ICMPv6 errors without replying to prohibited packet classes > Use RFC 4443 — Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification to review this narrow operational decision without extending the source beyond its stated scope. - Canonical URL: https://update.dsesecurity.com/updates/generate-icmpv6-errors-without-replying-to-prohibited-packet-classes/ - Publisher: Detection Systems & Engineering (DSE Security) - Author: DSE Security Editorial Team - Published: 2026-08-27T12:16:29+00:00 - Modified: 2026-08-27T12:36:16+00:00 - Last reviewed by DSE: 2026-08-26 - Resource type: Checklist - DSE priority: Advisory - Topics: IT, Networks & Infrastructure - Reading time: 3 minutes ## What you need to know Use RFC 4443 — Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification 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 RFC 4443 — Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification ## DSE recommendation Compare the observed state with the cited official source, document applicability and exceptions, and test any approved change with rollback safeguards. ## Article Treat this document as a focused evidence review: Generate ICMPv6 errors without replying to prohibited packet classes. Only the official source and traced locations below supply facts. Confirm applicability before acting. ## Source fact: The official [RFC 4443 — Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification](https://www.rfc-editor.org/rfc/rfc4443.html) from RFC Editor / Internet Engineering Task Force supports the following bounded statements: - An ICMPv6 error must not be generated in response to another ICMPv6 error or to an ICMPv6 Redirect message. The research record locates this support at Section 2.4 (Message Processing Rules), rules e.1 and e.2. - An error must not answer IPv6 or link-layer multicast, except for Packet Too Big and the defined Parameter Problem Code 2 case. The research record locates this support at Section 2.4 (Message Processing Rules), rules e.3 and e.4. - An error must not be generated for a packet whose source does not uniquely identify one node, including unspecified, multicast, or known anycast sources. The research record locates this support at Section 2.4 (Message Processing Rules), rule e.6. 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. ## 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. 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. ## Applicability questions - For source statement 1 at Section 2.4 (Message Processing Rules), rules e.1 and e.2, which observable configuration, record, or test can confirm applicability here? - For source statement 2 at Section 2.4 (Message Processing Rules), rules e.3 and e.4, which observable configuration, record, or test can confirm applicability here? - For source statement 3 at Section 2.4 (Message Processing Rules), rule e.6, 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. 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. 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 Tie each conclusion back to Section 2.4 (Message Processing Rules), rules e.1 and e.2; Section 2.4 (Message Processing Rules), rules e.3 and e.4; Section 2.4 (Message Processing Rules), rule e.6 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. Close the review only when the evidence, exception handling, resulting action, and after-state are linked. Schedule a new review after material technical, organizational, incident, or source changes; today’s observation is not a continuing guarantee. ## Official references - [RFC 4443 — Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification](https://www.rfc-editor.org/rfc/rfc4443.html) — RFC Editor / Internet Engineering Task Force ## Primary reference - Name: RFC 4443 — Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification - Authority: www.rfc-editor.org - URL: https://www.rfc-editor.org/rfc/rfc4443.html - Source publication date: Not stated by the source ## Citation and use Preferred citation: “Generate ICMPv6 errors without replying to prohibited packet classes,” DSE Security, https://update.dsesecurity.com/updates/generate-icmpv6-errors-without-replying-to-prohibited-packet-classes/ 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.