Firewalls,NetworkAddressTranslation(NAT),andnetworkloggingandaccountingareallprovidedbyLinux'sNetfiltersystem,alsoknownbythenameofthecommandusedtoadministerit,iptables.TheiptablesinterfaceisthemostsophisticatedeverofferedonLinuxandmakesLinuxanextremelyflexiblesystemforanykindof