A firewall is a hardware and software tool that provides network security by filtering incoming, outgoing, and intranet traffic between a local network and the Internet or a network and a computer. Filtering is performed according to user-specified rules.
The word firewall comes from the German word Brandmauer, which literally means “fire wall”, i.e. a barrier that protects surrounding buildings from the spread of fire in a fire. A firewall also protects the device from external threats by removing or reducing unwanted communications.
What tasks the firewall performs include
- Scans for threats on the network;
- Blocks suspicious or denied connections to potentially vulnerable services;
- Controls access to network services;
- Protects against malware;
- Blocks unauthorized access attempts;
- Protects against spam and junk mail;
- Maintains corporate security at a high level.
How a firewall works
The firewall analyzes data packets at the input and, based on the selected settings, allows or denies traffic. The settings are selected by the system administrator, who specifies the allowed and denied addresses or ports. The firewall can block IP addresses, domain names and ports, and restrict traffic and malware.