Peripherals Devices

INTERMEDIARY DEVICE

Any networking device positioned between a Remote Access Service (RAS) server and a RAS client. Intermediary devices are third-party devices for performing security-related tasks such as authentication, encryption, and other functions. RAS on Microsoft Windows NT Server and on Windows 2000 Server supports intermediary devices.
How It Works
An intermediary device such as a security host can be positioned between a RAS server and its modem pool. Clients connecting to the modem pool must be authenticated by the security host before they can establish a connection with the RAS server. The security host thus provides an extra layer of security for remote access to the network. The security host might prompt the user for credentials, or the user might be required to use a security card to gain access to the network.
Intermediary Devices in a Network

Computer networks vary in scale from small work groups, local area networks (LANs) to some of the largest networks like the Internet. They are all created essentially from connections between computers. These devices make the data transfer and regulation of these networks possible. They are designed to serve many functions like making data flow control decisions, data encryption, data modulation and demodulation, provide network security and most importantly, provide point to point connectivity. Here are some of the prime examples.

Switches
Network switches or packet switches are devices that connect the various segments of a network, and their main function is switching packets of data. Also known as a network bridge, they switch processes and rout data at the level of the data link layer, which is second of the OSI model layers (concerned with physical addressing of data). A switch may also operate at the level of other OSI layers like the physical, network or transport layer. Multilayer switches act at different OSI layers simultaneously. Network switches play a vital role in the functioning of local area networks.

Routers
As its name suggests, a router is an intermediary device that regulates and routs data traffic between computer networks. It forwards data to various network destinations and controls flow of data between two or more logical subnets, which do not have the same network address in a large network. It selects the optimum path for data transfer between two points in a network. Routers are one of the most vital network devices that make data transmission possible.

Modem
A modem (modulator - demodulator) is an intermediary device that converts analog signals transferred over networks into digital signals and digital signals back to analog. They enable the transmission of digital data over analog mediums like telephone lines and optic fiber cables.

Wireless Access Points
A wireless access point (WAP) is an intermediary device in a network that connects various types of wireless communication devices to connect with wireless networks. The connectivity is made possible through Bluetooth and Wi-Fi technologies . It acts as an intermediary between wireless devices and wired devices that are part of a network.

Hub
Working at the physical layer of the OSI model, a hub is basically a connector between ethernet segments which also control the bandwidth sharing among connected computer terminals.

Repeater
Repeaters are network devices that carry out the task of maintaining signal strength over its transmission through a network. They regenerate data signals and amplify them for further transmission.

Firewall
A firewall is any hardware appliance or software designed to filter network traffic that passes through it according to certain criteria and trust levels set by the network administrator.

These were some of the most common devices that are part of every computer network at any scale. Some other examples of intermediary network devices are proxy servers, gateways and digital media receivers. Without them, the working of a computer network would be next to impossible!