Changes

[[File:Firewall-concept.png|thumbnail|A firewall stands between the LAN (Local network) and WAN (Internet)]]

[[File:Firewall-concept.png|thumbnail|A firewall stands between the LAN (Local network) and WAN (Internet)]]

A '''firewall''' is a system which filters network activity and permits presumably safe [[internet]]/intranet traffic while blocking suspicious or unwanted communication.<ref>“Definition of firewall in English by Oxford Dictionaries.” Oxford Dictionaries | English, Oxford Dictionaries, http://en.oxforddictionaries.com/definition/firewall. Accessed 6 Sept. 2017. </ref> There are several types of firewall and methods of filtering.

A '''firewall''' is a system which filters network activity and permits presumably safe [[internet]]/intranet traffic while blocking suspicious or unwanted communication.<ref>“Definition of firewall in English by Oxford Dictionaries.” Oxford Dictionaries | English, Oxford Dictionaries, http://en.oxforddictionaries.com/definition/firewall. Accessed 6 Sept. 2017.</ref> There are several types of firewall and methods of filtering.

==Physical and Virtual==

==Physical and Virtual==

To the outside world, there is only one device (the firewall) on the protected network. Even when a connection is permitted, the communication still passes through the firewall using a specified port.  Therefore, even active connections do not reveal the internal [[IP address]] of devices.<ref name="WhatIsMyIPAddress.com">“What is a Firewall?” WhatIsMyIPAddress.com, http://whatismyipaddress.com/firewall. Accessed 7 Sept. 2017.</ref><br />

To the outside world, there is only one device (the firewall) on the protected network. Even when a connection is permitted, the communication still passes through the firewall using a specified port.  Therefore, even active connections do not reveal the internal [[IP address]] of devices.<ref name="WhatIsMyIPAddress.com">“What is a Firewall?” WhatIsMyIPAddress.com, http://whatismyipaddress.com/firewall. Accessed 7 Sept. 2017.</ref><br />

However, many hardware firewalls (all but the newest types) often do not know what connections are being used for.  Most do not collect the packets and reassemble messages, so connections can be abused without the firewall knowing.  Even the ones which do attempt to analyze traffic can have difficulty understanding what is going on.<ref name="WhatIsMyIPAddress.com"/>

However, many hardware firewalls (all but the newest types) often do not know what connections are being used for.  Most do not collect the packets and reassemble messages, so connections can be abused without the firewall knowing.  Even the ones which do attempt to analyze traffic can have difficulty understanding what is going on.<ref name="WhatIsMyIPAddress.com"/>

Some firewall configurations also offer what is called a "DMZ." This is a separate section of the network which is protected from the outside, but also cannot communicate directly with the inside network--it must go through another firewall (or the same one again) first. Sometimes certain servers and honeypots are placed here.

Some firewall configurations also offer what is called a "DMZ." This is a separate section of the network which is protected from the outside, but also cannot communicate directly with the inside network—it must go through another firewall (or the same one again) first. Sometimes certain servers and honeypots are placed here.

===Software===

===Software===