Some network hubs have them installed for protection
Router
A device on a network are gateway, router, bridge, switch, hub, repeater, multilayer switch, protocol converter, bridge router, digital media receiver, proxy, firewall, and network address translator. A computer on a network is called a networking computer. http://en.wikipedia.org/wiki/Computer_networking_device
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wireless router is a hardware A modern router (wireless or not) is a box that has the electronics and connections (network port connectors, radio transmitter/receivers, antenna) to allow receiving and sending of network data. It also has software (usually firmware) to allow management of the router functionality and to perform the actual routing functions. Routers come with builtin software supplied by the manuacturer. Sometimes the manufacturer supplies updates to the router software to fix prolems in the router or to add functionality. Many routers can also be loaded with software provided from alternate none manufacturer sources to enhance its functionality or to repurpose the router entirely.
A brouter is a device .this brouter functions as both a bridge and a router. It can forward data between the networks serving lika a bridge, but can also route data to individual systems within a network...
NAT IS A FIREWALL -- inside a router and when on you have a hardware firewall protecting you
A firewall can be either hardware or software
bridge filters router directs
A router A firewall
A network bridge just expands the number of computers that can be connected to the router.
router,bridge
A Bridge Router or brouter is a network device that works as a bridge and as a router
Security between networks is implemented in an intermediary device (a router or firewall appliance) at the perimeter of the network. The firewall function performed by this device permits only known, trusted data to access the network.
router,bridge
With a router or firewall or bridge. LAN is Local Area Network (inside a building) WAN is Wide Area Network (building to building, but inside the same organization).
Router
A router can improve network security if it includes the use of NAT (network address translation) and/or a firewall.