IAS Radius Realms and Prefixes Do Not Work Per Design Specifications

• Microsoft Windows NT version 4.0 Option Pack
• Microsoft Internet Authentication Service
• Microsoft Commercial Internet System version 2.5
• Microsoft Internet Authentication Services for Remote Access Service version 1.0

SYMPTOMS

Radius realms and prefixes do not work as per the original design specification.

For example, define a Radius realm named "realmname" with an "m/" prefix that grants users logon access only to the mail service. When a dial-up user logs on to the Internet service provider (ISP) as "m/username", Radius sees the "m/" prefix and applies the Radius profile, which restricts the user account to accessing mail only. The "m/username" logon information is then forwarded to the Microsoft Commercial Internet System (MCIS) Membership server and the user is logged on with the appropriate restrictions.

If, however, the user logs on with an "M/" prefix, the Radius server does not apply the "m/" profile because the Radius server is case sensitive for realms and prefixes. The Radius server also forwards "M/username" to the MCIS Membership server, and the user is successfully logged on without the necessary restrictions. The Membership server successfully authenticates the user because it is case insensitive for prefixes and realms.

So, if a user types a realm and prefix in a different case than was originally defined, the user bypasses the restrictions defined in the profile on the Radius server. ISPs have no way to limit user access to the services that they are providing to their users.

RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

   Date      Time                 Size    File name     Platform
   -------------------------------------------------------------
   9/3/99    8:48am              231,680  Authsrv.exe   x86
   9/3/99    8:49am              347,408  Authsrv.exe   Alpha 

STATUS

Microsoft has confirmed this to be a problem in Microsoft Windows NT 4.0.

Additional query words:

Keywords : kbbug4.00 kbfix4.00
Version : winnt:1.0,2.5
Platform : winnt
Issue type : kbbug