network access server
Abbreviated as NAS, a network access server is an access gateway between an external communications network and an internal network. A common use of NAS is by Internet service providers (ISP) where the user dials into the ISP and is given access to the Internet after being authorized by the access server. Network access server (NAS) is also referred to as a remote access server (RAS) or as a media gateway. The IETF Network Access Server Requirements Working Group is responsible for defining the requirements for modern network access servers.