Windows Sharing: Troubleshoot Unauthenticated Guest Access

If you're working on a Windows-based system, and receive an error about "security policies blocking unauthenticated guest access", when attempting to access a needed share, it is possible to bypass the default security policy.

The error is due to a domain policy that assumes that freely accessible shares (no passwords required) are likely to be unsafe (following the premise that only bad neighborhoods have doors without locks). Follow the steps below to set a local security policy to enable use of a password-less share.

1. While attempting to connect to a Windows-share UNC path, such as \\nmr-400.dept.lehigh.edu\topspin_data, you receive an error message like this:

2. Open an elevated command prompt by clicking Start, and typing 'cmd' (without hitting return). In the menu item that pops up, click on 'Run as Administrator'. Approve the alert, and type in your credentials, if asked.

3. At the command prompt that appears, type 'gpedit.msc' and hit return.

4. In the Local Group Policy Editor, in the left-hand pane, click on 'Computer Configuration > Administrative Templates > All Settings'

5. In 'Actions' menu, select 'Filter Options'.

6. In the Filter Options window, put a check next to 'Enable Keyword Filters', and type 'insecure' and click 'OK'.

7. Back in the left pane, check that you've navigated to 'Computer Configuration' > 'Administrative Templates' > 'All Settings', and in the right-hand pane, you should see the 'Enable insecure guest logons' item. on it to edit the policy.

9. Click the 'Enable' radio button to enable the policy, and click OK, and select 'Exit' from the File menu to quit the policy editor.

10. Now, re-try accessing the share. You should avoid the error, and have access to the files.