Internet Authentication Service

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Internet Authentication Service

Internet Authentication Service (IAS) in Microsoft® Windows Server® 2003, Standard Edition; Windows Server 2003, Enterprise Edition; and Windows Server 2003, Datacenter Edition is the Microsoft implementation of a Remote Authentication Dial-in User Service (RADIUS) server and proxy. As a RADIUS server, IAS performs centralized connection authentication, authorization, and accounting for many types of network access including wireless, authenticating switch, and remote access dial-up and virtual private network (VPN) connections. As a RADIUS proxy, IAS forwards authentication and accounting messages to other RADIUS servers. RADIUS is an Internet Engineering Task Force (IETF) standard. For more detailed information, see Features of IAS.

• Before installing an IAS server, see IAS checklists.

• For tips about using IAS, see IAS Best Practices.

• For help with specific tasks, see IAS How To....

• For general background information, see IAS Concepts.

• For problem-solving instructions, see IAS Troubleshooting.

Notes

• This feature is not included on computers running the Microsoft® Windows Server® 2003, Web Edition, operating system. For more information, see Overview of Windows Server 2003, Web Edition.

• You can configure IAS in Windows Server 2003, Standard Edition, with a maximum of 50 RADIUS clients and a maximum of 2 remote RADIUS server groups. You can define a RADIUS client using a fully qualified domain name or an IP address, but you cannot define groups of RADIUS clients by specifying an IP address range. If the fully qualified domain name of a RADIUS client resolves to multiple IP addresses, the IAS server uses the first IP address returned in the DNS query. With IAS in Windows Server 2003, Enterprise Edition, and Windows Server 2003, Datacenter Edition, you can configure an unlimited number of RADIUS clients and remote RADIUS server groups. In addition, you can configure RADIUS clients by specifying an IP address range.