How to enable CHAP on Radius server (NPS) when using CHAP for Radius authentication on the firewall
03/26/2020 
20 
16076
DESCRIPTION:
When using CHAP as Radius authentication type on the firewall, comparing to other authentication protocol, CHAP is disabled on the Radius server by default. This article will show you how to enable CHAP on the Radius server (in this case, using Windows Server 2008 NPS For demonstration).
RESOLUTION:
To enable CHAP-based authentication on server 2008, you must follow the below steps.
- Enable CHAP as an authentication protocol on the remote access server.
- Enable CHAP on the appropriate remote access policy.
- Enable storage of a reversibly encrypted form of the user's password.
- Force a reset of the user's password so that the new password is in a reversibly encrypted form.
Step 1: Enable CHAP as an authentication protocol on the remote access server.
1. Login Windows Server 2008 | Open Server Manager | Right click Routing and Remote Access.
2.
Select Properties | Click tab Security | Click Authentication Methods...
3.
Tick the square box at Encrypted authentication (CHAP).
Note: If you cannot find the Routing and Remote Access service, please check whether this role has been installed on the Windows Server 2008.
Step 2: Enable CHAP on the appropriate remote access policy.
1. Go to NPS > Policies > Network Policies.
2. Double click the policy you created for Radius authentication ( in this case, the policy name is SonicWall Group auth). | Click tab Constraints. | Select Encrypted authentication (CHAP) in Authentication Methods area and click OK.
Step 3: Enable storage of a reversibly encrypted form of the user's password.
1. Go to Active Directory Domain Services > Active Directory Users and Computers > Domain (e.g. scc.seeg.com) > Users
2. Double click the user which is going to use CHAP authentication protocol | Click tab Account | Select Store password using reversible encryption | Click OK
Note: When 'Store passwords using reversible encryption' is enabled (per user or for the entire domain), Windows stores the password encrypted, but in such a way that it can reverse the encryption and recover the plaintext password. This feature exists because some authentication protocols require the plaintext password to function correctly, the two most common examples are HTTP Digest Authentication and CHAP.
Step 4: Force a reset of the user's password so that the new password is in a reversibly encrypted form.
Right click the user | select Reset Password | set the password | Click OK
How to test:
1. Login to SonicWall | Go to Users > Settings page | Click Configure RADIUS
2. Click tab Test in the pop-up window | Input User and Password | Select CHAP | Click button Test.
The test status shows Radius Client Authentication Succeeded. Resolution for SonicOS 6.5
This release includes significant user interface changes and many new features that are different from the SonicOS 6.2 and earlier firmware. The below resolution is for customers using SonicOS 6.5 firmware.
To enable CHAP-based authentication on server 2008, you must follow the below steps.
- Enable CHAP as an authentication protocol on the remote access server.
- Enable CHAP on the appropriate remote access policy.
- Enable storage of a reversibly encrypted form of the user's password.
- Force a reset of the user's password so that the new password is in a reversibly encrypted form.
Step 1: Enable CHAP as an authentication protocol on the remote access server.
- Login Windows Server 2008 | Open Server Manager | Right click Routing and Remote Access.
- Select Properties | Click tab Security | Click Authentication Methods.
- Tick the square box at Encrypted authentication (CHAP).
Note: If you cannot find the Routing and Remote Access service, please check whether this role has been installed on the Windows Server 2008.
Step 2: Enable CHAP on the appropriate remote access policy.
- Go to NPS > Policies > Network Policies.
- Double click the policy you created for Radius authentication ( in this case, the policy name is SonicWall Group auth). | Click tab Constraints. | Select Encrypted authentication (CHAP) in Authentication Methods area and click OK.
Step 3: Enable storage of a reversibly encrypted form of the user's password.
- Go to Active Directory Domain Services > Active Directory Users and Computers > Domain (e.g. scc.seeg.com) > Users.
- Double click the user which is going to use CHAP authentication protocol | Click tab Account | Select Store password using reversible encryption | Click OK
Note: When 'Store passwords using reversible encryption' is enabled (per user or for the entire domain), Windows stores the password encrypted, but in such a way that it can reverse the encryption and recover the plaintext password. This feature exists because some authentication protocols require the plaintext password to function correctly, the two most common examples are HTTP Digest Authentication and CHAP.
Step 4: Force a reset of the user's password so that the new password is in a reversibly encrypted form.
Right click the user | select Reset Password | set the password | Click OK
How to test:
- Login to SonicWall Management Interface
- Click Manage in the top navigation menu
- Navigate to Users | Settings
- Click Configure Radius
- Click tab Test in the pop-up window | Input User and Password | Select CHAP | Click button Test.
The test status shows Radius Client Authentication Succeeded.
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