Hotfix for Windows 7 DirectAccess Clients

This month Microsoft released an important hotfix to address a DirectAccess connectivity issue for Windows 7 clients connecting to a Windows Server 2012 DirectAccess Server. The hotfix specifically resolves an issue where Windows 7 clients face a very long delay reestablishing a DirectAccess session using the IP-HTTPS IPv6 transition protocol after recently disconnecting from a VPN session. In this scenario, Windows 7 DirectAccess clients may take as long as 15 minutes to automatically reestablish a DirectAccess session using IP-HTTPS. During this time the IP-HTTPS adapter state is displayed as disconnected. Refer to Microsoft KB 2796313 more information and to download the hotfix.

Windows Server 2012 DirectAccess IP-HTTPS and Windows 7 Clients

With Windows Server 2008 R2, IP-HTTPS used standard SSL cipher suites to encrypt sessions. However, those sessions are already encrypted using IPsec, which is needlessly redundant. The protocol overhead for this double encryption placed an extreme burden on the DirectAccess server in terms of CPU utilization and memory consumption. Throughput and performance suffered greatly in large deployments. To address this issue, Microsoft included two new SSL cipher suites in Windows Server 2012 and Windows 8 that use NULL encryption. IP-HTTPS sessions are fully authenticated, but encrypted only once using IPsec. This significantly reduced resource demand on the DirectAccess gateway and improves performance greatly. Unfortunately, only Windows 8 clients can take advantage of this new IP-HTTPS functionality in Windows Server 2012 DirectAccess. When Windows 7 clients establish an IP-HTTPS session with a Windows Server 2012 DirectAccess gateway they will still request the use of fully encrypted cipher suites, as shown here:

Windows 7 IP-HTTPS Client Hello

Windows 7 DirectAccess IPHTTPS Cipher Suites

Windows 8 IP-HTTPS Client Hello

Windows 8 DirectAccess IPHTTPS Cipher Suites

Windows 8.1 IP-HTTPS Client Hello

Windows 8.1 DirectAccess SSL Cipher Suites

So, if you want to take advantage of the IP-HTTPS performance improvements in Windows Server 2012 DirectAccess, be sure to use Windows 8 clients!

Update: Recently with the help of the folks at F5, I developed a solution to emulate Windows 8 client behavior for Windows 7 DirectAccess clients using the F5 BIG-IP Local Traffic Manager (LTM). Using this technique allows you to *effectively* offload SSL for Windows 7 DirectAccess clients. Fore more details click here.

Presenting DirectAccess at Microsoft TechDays Belgium 2013

Join me in Belgium for Microsoft TechDays 2013! The event takes place at Kinepolis in Antwerp on March 5-6-7. I will be presenting a session on DirectAccess in Windows Server 2012 on March 7. The event will include sessions from many top speakers including Marcus Murray, Paula Januskiewicz, Tom Decaluwe, and more. There will be separate tracks for IT professionals and developers, so there will be something of interest to everyone. In addition, all attendees will receive a free 3 month TechNet subscription. Register today and don’t miss out on this amazing event!

Microsoft TechDays Belgium 2013

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