<Li> Protocol converter: a hardware device that converts between two different types of transmission, for interoperation . </Li> <Li> Bridge router (brouter): a device that works as a bridge and as a router . The brouter routes packets for known protocols and simply forwards all other packets as a bridge would . </Li> <P> Hardware or software components which typically sit on the connection point of different networks (for example, between an internal network and an external network) include: </P> <Ul> <Li> Proxy server: computer network service which allows clients to make indirect network connections to other network services . </Li> <Li> Firewall: a piece of hardware or software put on the network to prevent some communications forbidden by the network policy . A firewall typically establishes a barrier between a trusted, secure internal network and another outside network, such as the Internet, that is assumed to not be secure or trusted . </Li> <Li> Network address translator (NAT): network service (provided as hardware or as software) that converts internal to external network addresses and vice versa . </Li> </Ul>

Which network hardware component operates through all seven layers of osi model