Network Access Server is a server (application) that is used to authenticate and authorize a user (application/user/dial-up call etc) to use a shared resource such as internet etc. There could be various examples of it, such a NAS authenticate a user to use internet as user provides user-name and password n dial-up call.
As DIAMETER protocol is frequently used for AAA Authentication, Authorization and Accounting therefore applications based on DIAMETER that fulfill NAS requirement shall be very useful in telecom world.
Here in this article the intention is to explain, Diameter Network Access Server Application that complaint RFC-4005
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