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Assistance Needed with Firefox Browser and Group Policy Settings

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  • Last reply by Mike Kaply

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Hi there,

We are currently utilizing Windows Server 2019 as our development server. To maintain security protocols, we have implemented a Group Policy to block internet access on this server. Initially, this configuration successfully restricted internet access on all browsers, including Firefox. However, recently we encountered an issue where internet access became available solely through the Firefox browser, posing a significant data security risk.

Upon investigation, we discovered that Firefox allows users to modify proxy settings, effectively bypassing our Group Policy restrictions. Unlike other browsers, Firefox permits users to adjust proxy settings without sufficient rights, thus overriding our established restrictions.

To mitigate this issue, we require guidance on enforcing Group Policy settings within Firefox to prevent unauthorized alterations to proxy settings and ensure internet access remains restricted. It's important to note that Firefox is exclusively utilized for development purposes on our server.

Your assistance in resolving this matter would be greatly appreciated.

Regards, Hiten

Hi there, We are currently utilizing Windows Server 2019 as our development server. To maintain security protocols, we have implemented a Group Policy to block internet access on this server. Initially, this configuration successfully restricted internet access on all browsers, including Firefox. However, recently we encountered an issue where internet access became available solely through the Firefox browser, posing a significant data security risk. Upon investigation, we discovered that Firefox allows users to modify proxy settings, effectively bypassing our Group Policy restrictions. Unlike other browsers, Firefox permits users to adjust proxy settings without sufficient rights, thus overriding our established restrictions. To mitigate this issue, we require guidance on enforcing Group Policy settings within Firefox to prevent unauthorized alterations to proxy settings and ensure internet access remains restricted. It's important to note that Firefox is exclusively utilized for development purposes on our server. Your assistance in resolving this matter would be greatly appreciated. Regards, Hiten

All Replies (5)

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Are you using the Proxy enterprise policy with "Mode" set to "system" and "Locked" set to "true"?

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We have enabled the "Prevent changing proxy settings" policy from the Group Policy Management Console. However, we've encountered an issue where Firefox browser overrides this policy. It has come to our attention that Firefox is the only browser that allows users to change the default Windows proxy settings directly from the browser itself. We understand this thing from the following link

https://www.digitalcitizen.life/how-set-proxy-server-all-major-internet-browsers-windows/

To address this, we want to prevent users from changing proxy settings via Firefox browser as well. Could you please provide guidance on how to disable this feature?

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zeroknight said

Are you using the Proxy enterprise policy with "Mode" set to "system" and "Locked" set to "true"?

We have implemented the "Prevent changing proxy settings" policy through the Group Policy Management Console. However, we've observed that Firefox browser overrides this policy. Upon investigation, we discovered that Firefox uniquely allows users to modify the default Windows proxy settings directly from the browser.

To ensure consistency in proxy settings management, we aim to restrict users from altering proxy settings via the Firefox browser as well. We seek guidance on how to effectively disable this capability.

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> We have implemented the "Prevent changing proxy settings" policy through the Group Policy Management Console. However, we've observed that Firefox browser overrides this policy. Upon investigation, we discovered that Firefox uniquely allows users to modify the default Windows proxy settings directly from the browser.

Are you setting any other proxy policies besides this one?

I think you are running into

https://bugzilla.mozilla.org/show_bug.cgi?id=1876555