Dears,
I use NAT rule when I block all hosts and have a access list.
All services works ok. No MSN, no Orkut (tks Good).. etc.
But costumer need to use Skype.
What list of hosts I need to unblock to skype works?
Tks a Lot,
Ademir Peixoto
It’s impossible to block skype. It will work in any case, even if only port 80 is open. Customer must have some other kind of problem, - is the internet working at all?
There are people who ask us how to block skype, but it’s not easy 
Chinese “big firewall” able to block Skype as i heard
Impossible is nothing. But it’s very hard. Skype can connect even over port 80, or SSL. It encrypts itself, so it’s not possible to detect it. What one could do, is find out the servers that skype connects to initially after installation, but they change in different versions. Also, if skype connects for the first time, it downloads a list of new servers. So … tracking is possible, but will take complicated algorithms, lots of CPU resources, and updates for each Skype version.