A '''firewall''' is a system which filters network and permits presumably safe [[internet]]/intranet traffic while blocking suspicious or unwanted communication. There are several types of firewall and methods of filtering.
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A '''firewall''' is a system which filters network and permits presumably safe [[internet]]/intranet traffic while blocking suspicious or unwanted communication.<ref>https://en.oxforddictionaries.com/definition/firewall</ref> There are several types of firewall and methods of filtering.<br />
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'''See answers'''
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*Hardware vs Software: http://whatismyipaddress.com/firewall