FirewallA Firewall is a security system which avoids the interventions of foreign systems in an IT network.

The Firewall separate a private network (yours for example) from the public one by an invisible wall which prevent every persons, applications (a virus or a spyware), ... wanting to connect to your private space by filtering the ip addresses and allows to pass only the communications comming from the autorised addresses.

There are many types of Firewalls :

-Stateless Firewalls: The oldest type of Firewalls. It analyses information packages one by one independently. It is not very safe. That is why engineers creates the Stateful Firewalls.

-Stateful Firewalls: It is the second version of Firewalls. This time, it analyses information packages and verify that the package is the continuation of the previous one. It is the most wide-spread version.

-Application Layer Firewalls: The third and last Firewalls version. It verify the complete conformity of the packages with an expected protocol. It is used because more and more protocols use tunnels to avoid the port filtering. This version needs too much ressources if there is a huge flow level of information. That is the reason why it isn't used everywhere.

World Cloud Hosting, by providing you Linux distributions in the VPS solutions, watch your safety and your use comfort. Linux distributions are equipped with a secure Stateful Firewall called "iptables", which don't need too many ressources as the Application Layer Firewalls.