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Since Linux servers may be connected to the Internet, it is very important to run a firewall to control what comes into the computer system, what goes out of the computer system, and what may be forwarded to another computer. Linux uses the command called '''iptables''' to set the firewall rules. Although graphical programs can be used to configure iptables, it is important for students of Linux Administration to learn how to use the iptables command for more complex and automated configuration via shell scripting.