While integrating the RADIUS authentication with SonicWall with a Windows 2003 Server; the PAP, MSCHAP, and MSCHAPv2 work except CHAP. And while testing the RADIUS authentication; you receive the following error message:
“Radius Client Authentication Failed”
In order to support CHAP, user passwords must be stored using reversible encryption in the Operating System. On Windows the “Store passwords using reversible encryption” security policy security setting determines whether the operating system stores passwords using reversible encryption.
This policy provides support for applications that use protocols that require knowledge of the user's password for authentication purposes. Storing passwords using reversible encryption is essentially the same as storing plaintext versions of the passwords. For this reason, this policy should never be enabled unless application requirements outweigh the need to protect password information. This policy is disabled by default and that’s why the RADIUS auth fails with CHAP.
Enable the “Store passwords using reversible encryption” security option for the users under user properties on the Domain Controller.
Enable the “Store passwords using reversible encryption” security option on the Group Policy.
NOTE: The user need to change the password after enabling this security option then only CHAP will be activated for that user.
On the RADIUS server:
In the “Remote Access Policy” for the SonicWall device; CHAP should be enabled.
• Open up Internet Authentication Service mmc snap-in.
• Under “Remote Access Policy”, right click on the SonicWall policy and click on Properties.
• Click on “Edit Profile” button.
• On the “Authentication” tab make sure that “Encrypted Authentication (CHAP)” is checked.
After performing the above steps the user should be able use CHAP with RADIUS authentication on SonicWall.