Remote Access Service

Remote Access Services (RAS) refers to any combination of hardware and software to enable the remote access tools or information that typically reside on a network of IT devices.

Remote Access Service (RAS) connects a client to a host computer, known as a remote access server. To use RAS from a remote node, a RAS client program is needed, or any client software. Most remote control programs work with RAS. PPP is a set of industry standard framing and authentication protocols that enable remote access.

The term was originally coined by Microsoft when referring to their built-in Windows NT remote access tools. RAS is a service provided by Windows NT which allows most of the services which would be available on a network to be accessed over a modem link. The service includes support for dialup and logon, presents the same network interface as the normal network drivers (albeit slightly slower). RAS works with several major network protocols, including TCP/IP, IPX, and . It is not necessary to run Windows NT on the client - there are client versions for other Windows operating systems. RAS enables users to log in to an NT-based LAN using a modem, X.25 connection or WAN link.

Starting in the mid-1990s, several manufacturers such as U.S. Robotics produced "modem terminal servers". Instead of having RS-232 ports, these would directly incorporate an analog modem. These devices were commonly used by Internet service providers to allow consumer dial-up. Modern versions interface to an ISDN PRI instead of having analog modem ports.

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