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ERROR_IPSEC_DOSP_INVALID_PACKET
Malformed negotiation traffic fails before a usable security association exists
ERROR_IPSEC_DOSP_INVALID_PACKET means the edge protection logic received a packet that was not correctly formatted for the IPsec negotiation path it was inspecting. The failure occurs before the packet can establish trusted flow state. It can result from truncation, incorrect encapsulation, a sender using the wrong protocol or port, middlebox damage, or intentionally malformed traffic.
Capture the packet at both the public interface and, when possible, before any tunnel or NAT processing. Compare length fields, exchange type, version, and payload chain with the expected IKE or AuthIP keying module. Increasing state-table or rate-limit capacity will not repair a malformed packet. Repeated events from diverse sources are more consistent with hostile internet noise than with one peer configuration error.
Diagnosis should stay at the packet layer
- Compare captures before and after tunnel decapsulation or other middleboxes.
- Check that the allowed keying module matches the packet format and destination port.
- Look for truncation, inconsistent payload lengths, and unsupported exchange versions.
- Separate isolated peer failures from broad unsolicited scanning.
References
- Microsoft: allowed DoSP keying modules and flags
- RFC 7296: IKEv2 message and payload format
- Microsoft: ERROR_IPSEC_DOSP_INVALID_PACKET definition
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