IIS: logging client certificate's thumbprint

Solution 1:

While I am not proficient in IIS in particular (I deal with Apache mostly), I would expect this is be a custom logging sort of thing.

The following page documents some of the advanced logging functionality of IIS; while it doesn't show SSL things in the screenshots, it may still be useful.

http://www.iis.net/learn/extensions/advanced-logging-module/advanced-logging-for-iis-custom-logging

Note also the doucmentation around IIS server variables, which I would expect to be able to be logged in a custom logging situation.

https://msdn.microsoft.com/library/ms524602.aspx

That page does list various Client Authentication server variables.

Cheers, Cameron