Firewalls

A firewall is a device or set of devices (hardware, software, or both) within a computer system or network which is configured to block unauthorized access while protecting authorized communication. Firewalls permit or deny computer applications based upon a defined set of rules/criteria. Firewalls are widely used to prevent unauthorized internet access to private networks, especially intranets. All data being communicated through an intranet must pass through a firewall, which searches all data and blocks data which does not meet specific security criteria.