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Glossary >

USR8200 Firewall/VPN/NAS User Guide


100Base-T Also known as Fast Ethernet, an Ethernet cable standard with a data transfer rate of up to 100 Mbps.

10Base-T An older Ethernet cable standard with a data transfer rate of up to 10 Mbps.

802.3 The IEEE (Institute of Electrical and Electronics Engineers)-defined specification that describes the characteristics of Ethernet (wired) connections.

Access point A device that exchanges data between computers on a network. An access point typically does not have any Firewall or NAT capabilities.

Adapter Also known as a network interface card (NIC). An expansion card or other device used to provide network access to a computer, printer, or other device.

Administrator A person responsible for planning, configuring, and managing the day-to-day operation of a computer network. The duties of an administrator include installing new workstations and other devices, adding and removing individuals from the list of authorized users, archiving files, overseeing password protection and other security measures, monitoring usage of shared resources, and handling malfunctioning equipment.

Application Level Gateways (ALGs) Some applications, such as FTP, TFTP, PPTP, and H323 require the support of special application-specific ALG modules in order to work inside the home network. Data packets associated with these applications contain information that allows them to be routed correctly. An ALG is needed to handle these packets and ensure that they reach their intended destinations. The USR8200 Firewall/VPN/NAS is equipped with a list of ALG modules in order to enable maximum functionality in the home network.

Authentication The process of identifying an individual, usually based on a username and password. In security systems, authentication is distinct from authorization, which is the process of giving individuals access to system objects based on their identity. Authentication merely ensures that the individual is who he or she claims to be, but says nothing about the access rights of the individual.

Bandwidth The amount of information, or size of file, that can be sent through a network connection at one time. A connection with more bandwidth can transfer information more quickly.

Bridge A device that forwards packets of information from one segment of a network to another. A bridge forwards only those packets necessary for communication between the segments.

Broadband connection A high-speed connection, typically 256 Kbps or faster. Broadband services include cable modems and DSL.

Broadband modem A device that enables a broadband connection to access the Internet. The two most common types of broadband modems are cable modems, which rely on cable television infrastructure, and DSL modems, which rely on telephone lines operating at DSL speeds.

Broadcast Broadcasting sends a message to everyone on the network whereas multicasting sends a message to a select list of recipients.

Bus A set of hardware lines used for data transfer among the components of a computer system. A bus essentially allows different parts of the system to share data. For example, a bus connects the disk-drive controller, memory, and input/output ports to the microprocessor.

Cable modem A device that enables a broadband connection to access the Internet. Cable modems rely on cable television infrastructure, in other words, the data travels on the same lines as for your cable television.

CAT 5 cable Abbreviation for Category 5 cable. A type of Ethernet cable that has a maximum data rate of 100 Mbps.

Channel A path or link through which information passes between two devices.

CHAP Challenge Handshake Authentication Protocol, a type of authentication in which the authentication agent (typically a network server) sends the client program a random value that is used only once and an ID value. The sender and peer must share a predefined secret.

Client Any computer or program that connects to, or requests the services of, another computer or program on a network. For a local area network or the Internet, a client is a computer that uses shared network resources provided by a server.

Client/server network A network of two or more computers that rely on a central server to mediate the connections or provide additional system resources. This dependence on a server differentiates a client/server network from a peer-to-peer network.

Computer name A name that uniquely identifies a computer on the network so that all its shared resources can be accessed by other computers on the network. One computer name cannot be the same as any other computer or domain name on the network.

Crossover cable A type of cable that facilitates network communications. A crossover cable is a cable that is used to interconnect two computers by crossing over (reversing) their respective pin contacts.

DHCP Acronym for Dynamic Host Configuration Protocol. A TCP/IP protocol that automatically assigns temporary IP addresses to computers on a local area network (LAN). The USR8200 Firewall/VPN/NAS supports the use of DHCP. You can use DHCP to share one Internet connection with multiple computers on a network.

DMZ Acronym for Demilitarized Zone. A collection of devices and subnets
placed between a private network and the Internet to help protect the
private network from unauthorized Internet users.

DNS Acronym for Domain Name System. A data query service chiefly
used on the Internet for translating host names into Internet addresses.
The DNS database maps DNS domain names to IP addresses, so that users can locate computers and services through user-friendly names.

Domain In a networked computer environment, a collection of computers that share a common domain database and security policy. A domain is administered as a unit with common rules and procedures, and each domain has a unique name.

Domain name An address of a network connection that identifies the owner of that address in a hierarchical format: server.organization.type. For example, identifies the Web server at the White House, which is part of the U.S. government.

Drive An area of storage that is formatted with a file system and has a drive letter. The storage can be a floppy disk (which is often represented by drive A), a hard disk (usually drive C), a CD-ROM (usually drive D), or another type of disk. You can view the contents of a drive by clicking the drive's icon in Windows Explorer or My Computer. Drive C (also known as the hard disk), contains the computer's operating system and the programs that have been installed on the computer. It also has the capacity to store many of the files and folders that you create.

Driver Within a networking context, a device that mediates communication between a computer and a network adapter installed on that computer.

DSL Acronym for Digital Subscriber Line. A constant, high-speed digital connection to the Internet that uses standard copper telephone wires.

DSL modem A device that enables a broadband connection to access the Internet. DSL modems rely on telephone lines that operate at DSL speeds.

Duplex A mode of connection. Full-duplex transmission allows for the simultaneous transfer of information between the sender and the receiver. Half-duplex transmission allows for the transfer of information in only one direction at a time.

Dynamic IP address The IP address assigned (using the DHCP protocol) to a device that requires it. A dynamic IP address can also be assigned to a gateway or router by an ISP.

Encryption The translation of data into a secret code. Encryption is the most effective way to achieve data security. To read an encrypted file, you must have access to a secret key or password that enables you to decrypt it.

Ethernet A networking standard that uses cables to provide network access. Ethernet is the most widely-installed technology to connect computers together.

Ethernet cable A type of cable that facilitates network communications. An Ethernet cable comes in a couple of types. There are twisted pair and coax Ethernet cables. Each of these allows data to travel at 10Mbit per second.

Firewall A security system that helps protect a network from external threats, such as hacker attacks, originating outside the network. A hardware Firewall is a connection routing device that has specific data checking settings and that helps protect all of the devices connected to it.

Firmware Software information stored in nonvolatile memory on a device.

Flash memory A type of memory that does not lose data when power is removed from it. Flash memory is commonly used as a supplement to or replacement for hard disks in portable computers. In this context, flash memory either is built in to the unit or, more commonly, is available as a PC Card that can be plugged in to a PCMCIA slot.

FTP Acronym for File Transfer Protocol. A standard Internet protocol for downloading, or transferring, files from one computer to another.

Gateway A device that acts as a central point for networked devices, receives transmitted messages, and forwards them. The USR8200 Firewall/VPN/NAS can link many computers on a single network and can share an encrypted Internet connection with wired and wireless devices.

Gateway address The IP address you use when you make a connection outside your immediate network.

Hexadecimal A numbering system that uses 16 rather than 10 as the base for representing numbers. It is therefore referred to as a base-16 numbering system. The hexadecimal system uses the digits 0 through 9 and the letters A through F (uppercase or lowercase) to represent the decimal numbers 0 through 15. For example, the hexadecimal letter D represents the decimal number 13. One hexadecimal digit is equivalent to 4 bits, and 1 byte can be expressed by two hexadecimal digits.

Host name The DNS name of a device on a network, used to simplify the
process of locating computers on a network.

Hub A device that has multiple ports and that serves as a central connection
point for communication lines from all devices on a network. When
data arrives at one port, it is copied to the other ports.

IEEE Acronym for Institute of Electrical and Electronics Engineers. A society of engineering and electronics professionals that develops standards for the electrical, electronics, computer engineering, and science-related industries. The IEEE (Eye-triple-E) is a non-profit, technical professional association of more than 377,000 individual members in 150 countries. The full name is the Institute of Electrical and Electronics Engineers, Inc., although the organization is most popularly known and referred to by the letters I-E-E-E.

Internet domain In a networked computer environment, a collection of computers that share a common domain database and security policy. A domain is administered as a unit with common rules and procedures, and each domain has a unique name.

Intranet A network within an organization that uses Internet technologies (such a Web browser for viewing information) and protocols (such as TCP/IP), but is available only to certain people, such as employees of a company. Also called a private network. Some intranets offer access to the Internet, but such connections are directed through a Firewall.

IP Acronym for Internet Protocol. The protocol within TCP/IP that is used to send data between computers over the Internet. More specifically, this protocol governs the routing of data messages, which are transmitted in smaller components called packets.

IP address Acronym for Internet Protocol address. IP is the protocol within TCP/IP that is used to send data between computers over the Internet. An IP address is an assigned number used to identify a computer that is connected to a network through TCP/IP. An IP address consists of four numbers (each of which can be no greater than 255) separated by periods, such as

ISO/OSI reference model Abbreviation for International Organization for Standardization Open Systems Interconnection reference model. An architecture that standardizes levels of service and types of interaction for computers that exchange information through a communications network. The ISO/OSI reference model separates computer-to-computer communications into seven protocol layers, or levels; each builds on and relies on the standards contained in the levels below it. The lowest of the seven layers deals solely with hardware links; the highest deals with software interactions at the program level. It is a fundamental blueprint designed to help guide the creation of hardware and software for networks.

ISP Acronym for Internet Service Provider. A company that provides individuals or companies access to the Internet.

Kbps Abbreviation for Kilobits per second. Data transfer speed, as through a modem or on a network, measured in multiples of 1,000 bits per second.

LAN Acronym for Local Area Network. A group of computers and other devices dispersed over a relatively limited area (for example, a building) and connected by a communications link that enables any device to interact with any other on the network.

MAC address Abbreviation for Media Access Control address. The address that is used for communication between network adapters on the same subnet. Each network adapter is manufactured with its own unique MAC address.

MAC layer Abbreviation for Media Access Control layer. The lower of two sub layers that make up the data-link layer in the ISO/OSI reference model. The MAC layer manages access to the physical network, so a protocol like Ethernet works at this layer.

Mapping A process that allows one computer to communicate with a resource located on another computer on the network. For example, if you want to access a folder that resides on another computer, you map to that folder, as long as the computer that holds the folder has been configured to share it.

Mbps Abbreviation for Megabits per second. A unit of bandwidth measurement that defines the speed at which information can be transferred through a network or Ethernet cable. One megabyte is roughly equivalent to eight megabits.

Modem A device that transmits and receives information between computers.

MPPE Acronym for Microsoft Point to Point Encryption. A means of representing Point to Point Protocol (PPP) packets in an encrypted form.

Multicast To transmit a single message to a select group of recipients. A simple example of multicasting is sending an e-mail message to a mailing list. Teleconferencing and videoconferencing also use multicasting, but require more robust protocols and networks.

NAT Acronym for Network Address Translation. The process of converting between IP addresses used within a private network and Internet IP addresses. NAT enables all of the computers on a network to share one IP address.

Network A collection of two or more computers that are connected to each other through wired or wireless means. These computers can share access to the Internet and the use of files, printers, and other equipment.

Network adapter Also known as a Network Interface Card (NIC). An expansion card or other device used to provide network access to a computer, printer, or other device.

Network name The single name of a grouping of computers that are linked together to form a network.

Packet A unit of information transmitted as a whole from one device to another on a network.

PAP Acronym for Password Authentication Protocol. The most basic form of authentication, in which a user's name and password are transmitted over a network and compared to a table of name-password pairs. Typically, the passwords stored in the table are encrypted. The Basic Authentication feature built into the HTTP protocol uses PAP.

Peer-to-peer network A network of two or more computers that communicate without using a central server. This lack of reliance on a server differentiates a peer-to-peer network from a client/server network.

PING A protocol for testing whether a particular computer is connected to the Internet by sending a packet to the computer's IP address and waiting for a response.

Port A physical connection through which data is transferred between a computer and other devices (such as a monitor, modem, or printer), a network, or another computer. Also, a software channel for network communications.

PPPoE Acronym for Point-to-Point Protocol over Ethernet. A specification for connecting users on an Ethernet network to the Internet by using a broadband connection (typically through a DSL modem).

PPTP IP Security A set of protocols developed to support secure exchange of packets at the IP layer. IPSec has been deployed widely to implement Virtual Private Networks (VPNs).

PPTP Point-to-Point Tunneling Protocol, a technology for creating Virtual Private Networks (VPNs). Because the Internet is essentially an open network, the Point-to-Point Tunneling Protocol (PPTP) is used to ensure that messages transmitted from one VPN node to another are secure. With PPTP, users can dial in to their corporate network via the Internet.

Profile A computer-based record that contains an individual network's software settings and identification information.

Protocol A set of rules that computers use to communicate with each other over a network.

Resource Any type of hardware (such as a modem or printer) or software (such as an application, file, or game) that users can share on a network.

Restore factory defaults The term used to describe the process of erasing your base station's current settings to restore factory settings. You accomplish this by pressing the Reset button and holding it for five or more seconds. Note that this is different from resetting the base station.

RJ-11 connector An attachment used to join a telephone line to a device such as a modem or the external telephone lines.

RJ-45 connector An attachment found on the ends of all Ethernet cables that connects Ethernet (wired) cables to other devices and computers.

Samba A software suite that provides seamless file sharing services to SMB/CIFS clients.

Server A computer that provides shared resources, such as storage space or processing power, to network users.

Shared folder A folder (on a computer) that has been made available for other people to use on a network.

Shared printer A printer (connected to a computer) that has been made available for other people to use on a network.

Sharing To make the resources associated with one computer available to users
of other computers on a network.

SNTP Acronym for Simple Network Time Protocol. A protocol that enables
client computers to synchronize their clocks with a time server over the

Static IP address A permanent Internet address of a computer (assigned by an ISP).

Straight-through cable A type of cable that facilitates network communications. An Ethernet cable comes in a couple of flavors. There is twisted pair, and coax Ethernet cables. Each of these allow data to travel at 10Mbit per second. Unlike the Crossover cable, straight-through cable has the same order of pin contacts on each end-plug of the cable.

Subnet A distinct network that forms part of a larger computer network. Subnets are connected through routers and can use a shared network address to connect to the Internet.

Subnet mask Typically, a subnet may represent all the machines at one geographic location, in one building, or on the same local area network (LAN). Having an organization's network divided into subnets allows it to be connected to the Internet with a single shared network address. Similar in form to an IP address and typically provided by an ISP. An example of a subnet mask value is

Switch A central device that functions similarly to a hub, forwarding packets to specific ports rather than broadcasting every packet to every port. A switch is more efficient when used on a high-volume network.

Switched network A communications network that uses switching to establish a connection between parties.

Switching A communications method that uses temporary rather than permanent connections to establish a link or to route information between two parties. In computer networks, message switching and packet switching allow any two parties to exchange information. Messages are routed (switched) through intermediary stations that together serve to connect the sender and the receiver.

TCP/IP Acronym for Transmission Control Protocol/Internet Protocol. A networking protocol that allows computers to communicate across interconnected networks and the Internet. Every computer on the Internet communicates by using TCP/IP.

Throughput The data transfer rate of a network, measured as the number of kilobytes per second transmitted.

USB Acronym for Universal Serial Bus. USB is a plug-and-play interface between a computer and add-on devices (such as audio players, joysticks, keyboards, telephones, scanners, and printers). With USB, a new device can be added to your computer without having to add an adapter card or even having to turn the computer off.

USB adapter A device that connects to a USB port.

USB connector The plug end of the USB cable that is connected to a USB port. It is about half an inch wide, rectangular, and somewhat flat.

USB port A rectangular slot in a computer into which a USB connector is inserted.

UTP Acronym for Unshielded Twisted Pair. A cable that contains one or more twisted pairs of wires without additional shielding. It's more flexible and takes less space than a shielded twisted pair (STP) cable, but it has less bandwidth.

Virtual server One of multiple Web sites running on the same server, each with a unique domain name and IP address.

VPN A Virtual Private Network (VPN) is a private Network that makes use of the public telecommunication infrastructure, maintaining privacy through the use of a tunneling Protocol and security procedures.

WAN Acronym for Wide Area Network. A geographically widespread network that might include many linked local area networks.

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