COMODO Firewall Pro is a freeware for life with full access to all its functions. We must uninstall other security program to install this software. Now, even though this firewall is a freeware, but it really can compete with other paid firewalls. All we need is a little knowledge in internet connection and if you don't, you can always go to its forum site and seek help. I went to its forum to ask for help and my questions were answered and I'm satisfied it them.
For P2P file sharing clients users like emule and bittorrents, there will be a problem; the specified port does not open. It remained close until I wrote a rule allowing my torrent client to listen to a port. And that is after I went to its forum. This is proof that no incoming or outgoing access will take place without a rule.
This COMODO Firewall Pro has four security monitoring; application monitor, component monitor, network monitor, and application behaviour analysis. So I know which programs are connecting to the internet, and which are been blocked due to suspicious behaviour; thank you to application behaviour analysis.
There are a bit discomfort because we have to determine whether to give a program rights to connect to internet when an alert pops up. Even there will be security advise to guide me, being a not-a-genius-in computer does torment my little mind. It needs time to understand and learn everything about this program and I suggest you to pay a visit to the forum because you can understand better on how to use and create your own rules.
Anyway, this is the best firewall and the best thing is it is free.