Can't access facebook n YM

Hello,

Hello,
how to know if computer or network is protected by a firewall or proxy?
because i can't access my facebook , it shows


The connection has timed out

The server at login.facebook.com is taking too long to respond.


* The site could be temporarily unavailable or too busy. Try again in a few
moments.

* If you are unable to load any pages, check your computer's network
connection.

* If your computer or network is protected by a firewall or proxy, make sure
that Firefox is permitted to access the Web.

other than that , i also can access my yahoo messenger..