AuthIP

AuthIP is a Microsoft proprietary extension of the IKE cryptographic protocol.{{Cite web |title=Authenticated Internet Protocol (AuthIP) - Windows Server® 2008 TCP/IP Protocols and Services [Book] |url=https://www.oreilly.com/library/view/windows-server-2008/9780735624474/ch18s07.html |access-date=2023-08-04 |website=www.oreilly.com |language=en}}{{Cite web |title=IKE and AuthIP IPsec Keying Modules - Black Viper {{!}} BlackViper.Com |url=https://www.blackviper.com/windows-services/ike-and-authip-ipsec-keying-modules/ |access-date=2023-08-04 |website=www.blackviper.com}} AuthIP is supported in Windows Vista and later on the client and Windows Server 2008 and later on the server. AuthIP adds a second authentication to the standard IKE authentication which, according to Microsoft, increases security and deployability of IPsec VPNs. AuthIP adds support for user-based authentication by using Kerberos v5 or SSL certificates.

AuthIP is not compatible with IKEv2,{{Cite web |title=About IKEv2 |url=https://www.sonicwall.com/support/technical-documentation/docs/sonicos-7-0-0-0-ipsec_vpn/Content/ipsec-vpn-types-vpn-security-about-ikev2.htm/ |access-date=2023-08-04 |website=www.sonicwall.com}} an IETF standard with similar characteristics;{{Cite report |url=https://datatracker.ietf.org/doc/rfc5996/ |title=Internet Key Exchange Protocol Version 2 (IKEv2) |last=Eronen |first=Pasi |last2=Nir |first2=Yoav |date=September 2010 |publisher=Internet Engineering Task Force |issue=RFC 5996 |last3=Hoffman |first3=Paul E. |last4=Kaufman |first4=Charlie}} however Windows 7 and Windows Server 2008 R2 also support IKEv2.{{Cite web |title=Windows Server 2008 Remote Access and Network Access Protection {{!}} Microsoft Press Store |url=https://www.microsoftpressstore.com/articles/article.aspx?p=2228452&seqNum=2 |access-date=2023-08-04 |website=www.microsoftpressstore.com}}