router 
This device routes data through a packet-switched network, such as the Internet, from one local-area network (LAN) or wide-area network (WAN) to another; or from a LAN to the Internet. Routers can be configured to allow only authorized machines to transmit data into the local network so that private information can remain secure. In addition to supporting dial-in and leased connections, routers also handle errors, keep network usage statistics, and handle security issues.