Each computer that is connected to the Internet (and, more generally, to any computer network) is likely to become a victim of a computer attack by a hacker. The methodology generally used by hackers consists of scanning the network (by randomly sending out data packets) in search of a connected computer. Once a computer is found, the hacker searches for a security weakness in order to exploit it and access the data on the machine.
For several reasons, this threat is even greater when the machine is permanently connected to the Internet:
- The targeted machine is likely to be connected but not monitored
- The targeted machine is generally connected with a greater bandwidth
- The targeted machine does not change or rarely changes IP addresses
Therefore it is necessary for both company networks and Internet users with cable or ADSL connections to protect themselves from network intrusions by installing a protection device.
What is a Firewall?
A firewall is a system that protects a computer or a computer network against intrusions coming from a third-party network (generally the Internet). A firewall is a system that filters data packets that are exchanged over the network. Therefore, it is a filtering gateway that comprises at least the following network interfaces:
- an interface for the network being protected (internal network)
- an interface for the external network
Firewall
The firewall system is a software system, often supported by dedicated network hardware, forming an intermediary between the local network (or the local computer) and one or more external networks. A firewall system can be set up on any computer that uses any system as long as:
- The machine is powerful enough to process the traffic
- The system is secure
- No other service other than the packet filtering service is running on the server
In the case that a firewall system is provided in a black box, the term "appliance" applies.
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