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Firewall (computing)
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<p>In <a href="/facts/Computing/Kghtm9fX">computing</a>, a firewall is a <a href="/facts/Network_security/09f8YxwD">network security</a> system that <a href="/facts/Network_monitoring/dt0cvIqS">monitors</a> and controls incoming and outgoing <a href="/facts/Network_traffic/sdUtmrxM">network traffic</a> based on configurable security rules. A firewall typically establishes a barrier between a trusted network and an untrusted network, such as the <a href="/facts/Internet/Xw1rVvJU">Internet</a> or between several <a href="/facts/VLAN/QhdJNaWX">VLANs</a>. Firewalls can be categorized as network-based or host-based. </p>