inverse monitoring

[Adrian Schmitt]

Hi,

I would like to monitor that some web pages are not available.
Is there some way to inverse the conditions?

Example (see line 5 "not"):

# 1 check host example.com with address nnn.nnn.nnn.nnn
# 2   if failed icmp type echo with timeout 3 seconds then alert
# 3   if failed port 80 protocol http then alert
# 4   if failed host public.example.com port 80 protocol http then alert
# 5   if NOT failed host internal.example.com port 80 protocol http then alert

In my case this would be very helpful to ensure that
some internal sites are only visible to the LAN and not to the public
internet.

I could not find such functionality in the documentation, did I
overlook something?
When I tried to insert "not" in the config file like in line 5 there
was an error, so I guess this is not the way to do it.

Thank you