avast 4.8 home free edition update

Hello

I am just installed avast 4.8 home free edition but, at home i Have a firewall so, i suppose that I should open some ports in order to allow avast update.

Which port should my firewall have open?

thank you.

No, not really. avast uses port 80 (http) to update.
avast.setup (a temporary file) should be allowed to connect in order to update.