We’ve been setting up Active Directory Federation Services (ADFS) on Windows Server 2012 R2 to tie up with Office365, and we ran into a snag with load balancing ADFS on our aging F5 BIG-IP LTM. It’s on the dinosaur end of the historical timeline, or to put it another way, “it’s in its sunset year”, and the latest supported code is 10.2.4.
This poses a bit of an issue with monitoring the ADFS servers, since the version shipping with Windows Server 2012 R2 includes a new SSL TLS feature called “Server Name Indication”, or SNI. The prehistoric 10.2.4 BIG-IP code doesn’t support SNI. Thankfully, Microsoft provides a way to monitor the servers over HTTP (instead of HTTPS), but the documentation we found–links below–was lacking an important detail.