Network access server definition
A network access server is a specialized server that acts as a gateway to a larger network.
See also: DSLAM, wireless network security, remote access server
How NAS works
- User authentication. The NAS verifies the credentials of users trying to access the network.
- Authorization. NAS determines the network resources and services that the user can access.
- Accounting. NAS tracks user activities (i.e., connection duration, amount of transferred data).
Examples of a network access server
- ISP dial-up access servers. A classic example of NAS: internet service providers use NAS to provide dial-up internet access to customers.
- DSL access multiplexers (DSLAMs). DSLAMs function as a type of NAS — they provide an aggregation point for multiple DSL connections.
- Wireless network access servers. In wireless networks (i.e., cellular networks, Wi-Fi hotspots), NAS devices manage the connection and authentication of wireless devices to the network.
- VPN servers. VPN servers act as NAS for users connecting to a private network over the internet. They authenticate users and encrypt traffic, providing secure access to network resources.
- Remote access servers (RAS). Businesses use dedicated servers to enable remote employees to dial into the company’s network securely, often using VPN technology.
- Cable modem termination systems (CMTS). In cable internet networks, CMTS devices function as NAS.
- Authentication servers. While not NAS themselves, servers running RADIUS or TACACS+ protocols work with NAS to authenticate and authorize users.
