FastCGI
From DAViCal Wiki
DAViCal can be made to work with fastCGI with a simple alteration to the fastcgi.conf file.
Find the FastCgiConfig directive FastCgiConfig -minProcesses 1 -maxProcesses 10 -singleThreshold 100
Add "-pass-header AUTHORIZATION" to the end
This is required because FastCGI doesn't by default pass the authentication headers to the caldav.php script, and authentication will therefore inevitably fail.
You will also need to be running version 0.9.4 or later, which includes specific changes to support the FastCGI authentication variables. Alternatively you can apply the patch here to 0.9.3.

