Comodo's Firewall is the first layer of defense against viruses, worms, trojans, hackers and all Internet threats. Comodo's Firewall is using the Default Deny Protection to prevent the threat of that will happen,, Comodo Firewall cross references to the white list of more than 15 million trusted files and applications. If the file is requesting access to the list, Comodo Firewall can be sure it is safe for your computer to allow it to execute. If not, Comodo Firewall will tell you that the file may be dangerous is trying to enter your PC. The latest version to see great leaps forward in security and usability with the addition of cloud based scanning and analyzing the behavior of files that have not recognized - making Comodo Firewall unbeaten in detecting zero-day attacks. In the default setting, is unknown and untrusted files are automatically scanned by our cloud-based virus scanner that, while the file server is experiencing behavioral analysis in our cloud, running in a virtual environment (sandbox) on your local computer so it can not modify or affect the data on 'real' your system.