Windows 2000 Professional and Windows XP Professional do not support incoming connections by using MD5 Challenge Handshake Authentication Protocol (CHAP) for Point-to-Point Protocol (PPP) authentication

Unlike Microsoft Windows 2000 Server Remote Access Service, Microsoft Windows 2000 Professional does not support incoming connections by using MD5 Challenge Handshake Authentication Protocol (CHAP) for Point-to-Point Protocol (PPP) authentication. Windows XP Professional also does not support incoming connections by using MD5 CHAP for PPP authentication.

Note MD5 CHAP is supported as a client-side authentication protocol when Windows 2000 Professional is dialing in to a server that is running Windows 2000 Server.

By default, Windows 2000 Professional supports the following PPP authentication protocols:

• MS CHAP
• MS CHAP v2

To enable support for Password Authentication Protocol (PAP) and Shiva Password Authentication Protocol (SPAP), follow these steps on a Windows 2000 Professional-based computer that is receiving the incoming calls.

1. Double-click Network and Dial-up Connections, right-click Incoming Connections, and then click Properties.
2. Click the Users tab.
3. Click to clear the Require all users to secure their passwords and data check box.

Microsoft Windows NT 4.0 Professional supports MD5 CHAP.

For more information, click the following article number to view the article in the Microsoft Knowledge Base: For more information about how to enable CHAP MD5 support in Windows 2000 Server, click the following article number to view the article in the Microsoft Knowledge Base: