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Why Is a Firewall Necessary?

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Quick Answer

A firewall is necessary because it blocks unauthorized access to private networks, safeguarding them from hackers, viruses and worms. A firewall works by monitoring all messages entering and leaving the intranet and restricting those that do not meet security data. A firewall can take the form of hardware, software or a combination of both. Some of the most common forms are packet filtering, circuit-level gateway implementation and web application firewalls.

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Hackers, viruses and other online threats put computer users at risk of information theft and jeopardized computer performance. A firewall acts as the first line of defense against these threats. It checks network traffic and connections but does not authenticate individual users for access to a network.

In packet filtering, the system examines the packets that enter and leave the network. User-defined rules determine whether access is granted or declined. Packet filtering is susceptible to IP spoofing, the creation of IP packets with a forged IP address.

Circuit-level gateway implementation applies security mechanisms whenever a TCP or UDP is established. Upon authentication of a connection, packets flow between hosts without further revision.

A web application firewall is a hardware filter, such as a sever plug-in, that applies a pre-formulated set of rules to a HTTP conversation, thereby identifying and blocking attacks from malevolent sources.

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