strongSwan

h1. Requirements for certificates used with Windows 7

The Windows 7 Beta release was liberal in accepting certificates, but the Release Candidate adds new requirements for the VPN gateway certificate. 

h2. Required fields

Your gateway certificate must have:

* An *Extended Key Usage* flag explicitly allowing the certificate to be used for authentication purposes. It is currently unclear which OIDs are accepted by Windows, but it seems that the *serverAuth* EKU having the OID _1.3.6.1.5.5.7.3.1_ (often called _TLS Web server authentication_) is ok. If you are using OpenSSL to generate your certificates then include the option

  <pre>

extendedKeyUsage = serverAuth

</pre> 

  In Windows 7, you now have to add the "IP Security IKE Intermediate", this is done by adding the oid :  1.3.6.1.5.5.8.2.2 as extendedKeyUsage (a good page about ikev2/windows understanding is "this one":http://www.carbonwind.net/blog/post/VPN-Reconnect-in-Windows-7-RC-redux.aspx )

  Which give extendedKeyUsage = serverAuth, 1.3.6.1.5.5.8.2.2

* The hostname of the VPN gateway entered in the clients connection properties *MUST* be contained either in the *subjectDistinguishedName* of the server certificate

  <pre>

C=CH, O=strongSwan Project, CN=vpn.strongswan.org

</pre>

  or in a *subjectAltName* extension that can be added with the option

  <pre>

subjectAltName = DNS:vpn.strongswan.org

</pre>

h2. Disabling extended certificate checks

Alternatively, you may disable these extended certificate checks on the client. 

> *This is potentially dangerous, as any certificate holder assured by your CA may act as the VPN gateway.*

To disable the extended checks, add a _DWORD_ called *DisableIKENameEkuCheck* to

<pre>

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\RasMan\Parameters\

</pre>

in the client's registry.

h2. Further information

For more details about the requirements and other ways to disable the certificate checks, have a look to "this knowledge base article":http://support.microsoft.com/kb/926182.