Network access server: Difference between revisions

Revision as of 23:46, 11 November 2013

Revision as of 05:08, 15 January 2014

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{{Unreferenced|date=October 2009}}

A '''Networknetwork Accessaccess Serverserver''' ('''NAS''') is a single point of access to a remote resource.

==Overview==

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The above translates into different implementations for different uses. Here are some examples.

*An [[Internet Serviceservice Providerprovider]] which provides network access via common modem or modem-like devices (be it [[PSTN]], [[DSL]], [[cable modem|cable]] or [[GPRS]]/[[UMTS]]) can have one or more NAS (network access server) devices which accept [[Point-to-Point Protocol|PPP]], [[PPPoE]] or [[PPTP]] connections, checking credentials and recording accounting data via back-end [[RADIUS]] servers, and allowing users access through that connection.

*A sample use is the [[captive portal]] mechanism used by many [[WiFi]] providers: a user wants to access the Internet and opens a [[web browser|browser]]. The NAS detects that the user is not currently [[authorized]] to have access to the Internet, so the NAS prompts the user for their username and password. The user supplies them and sends them back to the NAS. The NAS then uses the [[RADIUS]] protocol to connect to an [[AAA protocol|AAA]] server and passes off the [[username]] and [[password]]. The RADIUS server searches through its resources and finds that the credentials are valid and notifies the NAS that it should grant the access. The NAS then grants the user access to the Internet.

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*Another use of a NAS would be in [[VoIP]]. However, instead of using a username and password, many times a [[phone number]] or [[IP Address]] are used. If the phone number is a valid customer then the call can be completed. Other uses might be if the phone number has [[long distance calling|long distance]] access or if a [[telephone card]] has minutes left.

==Associated Protocolsprotocols==

Although not required, NASs are almost exclusively used with [[AAA protocol|Authenticationauthentication, Authorizationauthorization, and Accountingaccounting]] (AAA) servers. Of the AAA protocols available, [[RADIUS]] tends to be the most widely used. The [[Diameter (protocol)|Diameter]] base protocol extends RADIUS services by providing error handling and inter-___domain communications. This protocol is used in networks like the [[IP Multimedia Subsystem]] (IMS).

==See also==

* [[Terminal server]]

==External links==

* RFC 2881, Network Access Server Requirements Next Generation (NASREQNG)