I have seen the check working on a demo and see it in their man page but can't get it to work.
I have the default command defined.
# 'check_http' command definition
command_line $USER1$/check_http -I $HOSTADDRESS$ $ARG1$
I have created the service
use local-service ; Name of service template to use
check_command check_http! -H www.domain.com -C 30
When I do the check from the command line it works
sudo ./check_http -H www.domain.com -C 30
OK - Certificate will expire on 03/05/2012 23:59.
But in Icinga (Nagios) it just says connection refused.