Applies to all Barracuda Web Filters, all firmware versions.
When a user tries to access a web site, from a network using NTLM authentication, Windows Vista and Windows 7 fails to send the user’s password to the Barracuda Web Filter. This happens because Windows Vista/Windows 7 uses NTLMv2 challenge/response authentication and the Barracuda Web Filter is expecting NTLMv1.
The solution is to force the Windows machine to use the older encryption method as follows:
Vista/7 Home Basic and Home Premium
- Go to Start > Run, to open a command prompt and then type regedit.
- Expand the folders for HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa.
- Double click to open and modify the LmCompatibilityLevel parameter.
- Type 1 in the Value Data field (replace the default value of 3).
- Click OK.
Windows Vista/7 Business, Enterprise, and Ultimate
- Go to Start > Control Panel > System and Maintenance > Administrative Tools > Local Security Policy.
- Click the triangle next to Local Policy > Security Options.
- Double click to open Network security: LAN Manager Authentication Level.
- Select Send LM & NTLM - Use NTLMv2 Session Security if Negotiated from the dropdown box.
- Click OK.
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