If you need to use a firewall to connect to the internet, you should specify the address of the firewall. If you find that you are getting constant 'Host not Found' messages, you should check and make sure that both the address and the port of your firewall are correct.
Specifies the port to use if using a firewall
Allows you to specify the username for authenticating firewalls
Allows you to specify the password for authenticating firewalls