Firewall
(noun)
 A gateway between the internet and a local network, allowing or denying access based upon protocols.
Examples of Firewall in the following topics:
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E-Mail as an Entry Point- Firewalls - Simply put, a firewall permits or denies communication from the network based upon specific parameters.
 
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Malware- Malware has caused the rise in use of protective software types such as anti-virus, anti-malware, and firewalls.
 
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Types of Networks- Virtual Networks may employ virtual security switches, virtual routers, virtual firewalls, and other virtual networking devices to direct and secure data traffic.