This subcategory reports the results of Internet Key Exchange (IKE) protocol and Authenticated Internet Protocol (AuthIP) during Main Mode negotiations. Events for this subcategory include: ? 4646: IKE DoS-prevention mode started. ? 4650: An IPsec Main Mode security association was established. Extended Mode was not enabled. Certificate authentication was not used. ? 4651: An IPsec Main Mode security association was established. Extended Mode was not enabled. A certificate was used for authentication. ? 4652: An IPsec Main Mode negotiation failed. ? 4653: An IPsec Main Mode negotiation failed. ? 4655: An IPsec Main Mode security association ended. ? 4976: During Main Mode negotiation, IPsec received an invalid negotiation packet. If this problem persists, it could indicate a network issue or an attempt to modify or replay this negotiation. ? 5049: An IPsec Security Association was deleted. ? 5453: An IPsec negotiation with a remote computer failed because the IKE and AuthIP IPsec Keying Modules (IKEEXT) service is not started. Refer to the Microsoft Knowledgebase article ?Description of security events in Windows Vista and in Windows Server 2008? for the most recent information about this setting: http://support.microsoft.com/default.aspx/kb/947226. Fix: (1) GPO: Computer Configuration\Windows Settings\Security Settings\Advanced Audit Policy Configuration\Audit Policies\Logon/Logoff!Audit Policy: Logon-Logoff: IPsec Main Mode (2) WMI: ###