Can you disable firewall and the anti virus on your windows desktop?
I spent a few hours with Nas to make something to work and it was from anti virus from my desktop …
The anti virus from my desktop takes control of the firewall rules and check also the ssl connections. I must to disable this on my AV to work with transparent proxy with ssl.
So, try to disable everything between desktop and NS: disable everything from desktop and the web filter from NS. Did you install the NS SSL Certificate on desktop?
Sorry for all of this (I bet that you are already upset and I don’t want to piss you more) but maybe you missed something. If Filippo said that it works, be sure of that!
Another thing, what NS did you run? 6.7 or 7 alpha2?
Edit:
take it like a joke: finally, try this: Firewall blocks Nagios