Make IIS require SSL client certificate during initial handshake

Here’s how I did this, on IIS 7.5:

1. Run the following in an admin command prompt: netsh http show sslcert

2. Save the output in a text file. Will look something like this:

   IP:port                 : 0.0.0.0:443
   Certificate Hash        : [a hash value]
   Application ID          : {[a GUID]}
   Certificate Store Name  : MY
   Verify Client Certificate Revocation    : Enabled
   Verify Revocation Using Cached Client Certificate Only    : Disabled
   Usage Check    : Enabled
   Revocation Freshness Time : 0
   URL Retrieval Timeout   : 0
   Ctl Identifier          : (null)
   Ctl Store Name          : (null)
   DS Mapper Usage    : Disabled
   Negotiate Client Certificate    : Disabled
   

3. Create a batch file using that info:

   netsh http show sslcert
   netsh http delete sslcert ipport=0.0.0.0:443
   netsh http add sslcert ipport=0.0.0.0:443 certhash=[your cert hash from above] appid={[your GUID from above]} certstorename=MY verifyclientcertrevocation=enable VerifyRevocationWithCachedClientCertOnly=disable UsageCheck=Enable clientcertnegotiation=enable
   netsh http show sslcert
   

   (Yes, you have to delete and re-add; you can’t just alter clientcertnegotiation in-place. That’s why it’s important to save the hash and GUID, so it knows what to re-add.)

4. Run that batch file, check for any errors, done.

Keep in mind that this setting is applied per-certificate, not per-server. So if you use multiple certs, or change/update your cert, you will have to do this again.