Use Fiddler to determine which connections Windows 10 establishes automatically

Martin Brinkmann
Aug 13, 2015
Updated • Jul 5, 2017
Windows, Windows 10

A lot has been found out about the data collection that is going on in Microsoft's new operating system Windows 10.

We have covered these issues in our Windows 10 privacy guide, but it became clear quickly that Windows was still phoning home at times even when you disable or block all options provided under settings and elsewhere.

Most users are probably unaware of this since it all happens in the background. You can check out Ars Technica's findings on the matter which provide you with details about network activity after turning off or disabling phone-home features such as Cortana or Web Search.

But what if you want to find out about that on your own? The following guide provides you with information on how to set up your own network monitor to get a detailed account on what is happening in the background when you are using your computer and when your computer is idle.

It works well for all kind of tasks, not only to monitor the operating system level but also applications or apps.

Note: Fiddler may not catch all network traffic even if you configure it to capture http and https traffic. As Ars Technica notes, Windows appears to use a content deliver network that bypasses network monitors.

It is recommended to run the program in a virtual machine as it needs to install a root certificate on the system in order to capture https traffic. While you can install the certificate on the underlying system as well, it is not recommended. If you still want to go ahead, make sure you remove it once you are done.

You need to download Fiddler4 from the developer website and install it afterwards. Start the program, and select Tools > Fiddler Options.

Switch to HTTPS and check the "Decrypt HTTPS traffic" box. Make sure all processes are listed and click ok. Fiddler displays its root certificate warning prompt which you need to accept to continue.

A security warning is displayed afterwards which you need to accept as well. You need to accept the User Account Control prompt as well to complete the process, and then that you "really" want to add the certificate.

Once you are back in the main interface select Stream in the main toolbar so that it is highlighted with a rectangular box around it.

Make sure capturing is listed in the lower left corner.

That's all you need to do and network traffic should start to show up in the interface as soon as it occurs. A simple example of this is the ping to when you use the search, even if you have disabled web search previously.

As soon as you start typing the first character in the search form, a ping to is sent by the operating system.

Remove the root certificate

root certificates

To remove the root certificate again, do the following:

  1. Tap on the Windows-key and type Certificate.
  2. Select "Manage user certificates" from the list of results.
  3. Open Trusted Root Certification Authorities > Certificates.
  4. Locate all (should be two) DO_NOT_TRUST_FiddlerRoot certificates.
  5. Select them and hit the delete key on the keyboard.
  6. Select yes when the prompt is displayed to remove it from the system.
Use Fiddler to determine which connections Windows 10 establishes automatically
Article Name
Use Fiddler to determine which connections Windows 10 establishes automatically
Find out how to set up a network monitoring environment on Windows 10 to detect when the operating system phones home.
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  1. Dan Donx said on January 15, 2023 at 10:29 am

    What mental age of reader are you targeting with the first sentence? 10?

    Why not write an article on how to *avoid* upgrading from W10 to W11. Analogous to those like me who avoided upgrading from 7 to 10 for as long as possible.

    If your paymaster Microsoft permits it, of course.

  2. Dexter said on January 15, 2023 at 11:14 am

    5. Rufus
    6. Ventoy

    PS. I hate reading these “SEO optimized” articles.

    1. cdr said on January 15, 2023 at 3:32 pm

      I used Rufus to create an installer for a 6th gen intel i5 that had MBR. It upgraded using Setup. No issues except for Win 11 always prompting me to replace my local account. Still using Win 10 Pro on all my other PCs to avoid the bullying.

  3. sv said on January 15, 2023 at 6:40 pm

    bit pointless to upgrade for the sake of upgrading as you never know when you’ll get locked out because ms might suddenly not provide updates to unsupported systems.

    ps…. time travelling?
    written. Jan 15, 2023
    Updated • Jan 13, 2023

    1. Martin Brinkmann said on January 16, 2023 at 5:49 am

      This happens when you schedule a post in WordPress and update it before setting the publication date.

  4. Anonymous said on January 16, 2023 at 8:24 am

    Anyone willing to downgrade to this awful OS must like inflicting themselves with harm.

  5. basingstoke said on January 16, 2023 at 11:18 am

    I have become convinced now that anybody who has no qualms with using Windows 11/10 must fit into one of the following brackets:

    1) Too young to remember a time before W10 and W11 (doesn’t know better)

    2) Wants to play the latest games on their PC above anything else (or deeply needs some software which already dropped W7 support)

    3) Doesn’t know too much about how computers work, worried that they’d be absolutely lost and in trouble without the “”latest security””

    4) Microsoft apologist that tries to justify that the latest “features” and “changes” are actually a good thing, that improve Windows

    5) Uses their computer to do a bare minimum of like 3 different things, browse web, check emails, etc, so really doesn’t fuss

    Obviously that doesn’t cover everyone, there’s also the category that:

    6) Actually liked W7 more than 10, and held out as long as possible before switching, begrudgingly uses 10 now

    Have I missed any group off this list?

    1. Heinz Strunk said on September 19, 2023 at 3:57 pm

      You have missed in this group just about any professional user that uses business software like CAD programs or ERP Programs which are 99% of all professional users from this list.

      Linux doesn’t help anyone who is not a linux kid and apple is just a fancy facebook machine.

  6. ilev said on August 24, 2023 at 7:34 pm

    Microsoft has removed KB5029351 update

    1. EP said on August 24, 2023 at 9:21 pm

      only from windows update though
      KB5029351 is still available from the ms update catalog site

  7. Anonymous said on August 24, 2023 at 11:05 pm

    1. This update is labaled as PREVIEW if it causes issues to unintelligent people, then they shouldn’t have allowed Preview updates ot install.

    2. I have installed it in a 11 years old computer, and no problems at all.

    3. Making a big drama over a bluescreen for an updated labeled as preview is ridiculous.

    This is probably another BS internet drama where people ran programs and scripts that modified the registry until they broke Windows, just for removing stuff that they weren’t even using just for the sake of it.
    Maybe people should stop playing geeks and actually either use Windows 10 or Windows 11, but don’t try to modify things just for the sake of it.

    Sometimes removing or stopping things (like defender is a perfect example) only need intelligence, not scripts or 3rd party programs that might mess with windows.

  8. john said on August 24, 2023 at 11:17 pm

    Windows 11 was a pointless release, it was just created because some of the Windows team wanted to boost sales with some sort of new and improved Windows 10. Instead, Microsoft cannot support one version well let alone two.

    1. John G. said on August 25, 2023 at 12:08 pm

      Windows 11 is the worst ugly shame by Microsoft ever. They should release with every new W11 version a complete free version of Starallback inside just to make this sh** OS functionally again.

  9. EP said on August 25, 2023 at 3:10 pm

    motherboard maker MSI has recently released a statement regarding the “unsupported processor” blue screen error for their boards using Intel 600/700 series chipsets & to avoid the KB5029351 Win11 update:–UNSUPPORTED-PROCESSOR–Error-Message-of-Windows-11-Update-KB5029351-Preview-142215

  10. EP said on August 29, 2023 at 7:32 pm

    check out the following recent articles:

    Neowin – Microsoft puts little blame on its Windows update after UNSUPPORTED PROCESSOR BSOD bug:

    BleepingComputer – Microsoft blames ‘unsupported processor’ blue screens on OEM vendors:

  11. Leonard Britvolli said on August 30, 2023 at 10:33 pm

    While there may be changes or updates to the Windows 10 Store for Business and Education in the future, it is premature to conclude that it will be discontinued based solely on rumors.

  12. sembrador said on September 5, 2023 at 9:32 pm

    My advice, I left win 15 years ago. Now I’m a happy linux user (linuxmint) but there is Centos, Fedora, Ubuntu depending on your needs.

  13. EP said on September 6, 2023 at 11:55 am

    motherboard maker MSI has recently released new BIOS/firmware updates for their Intel 600 & 700 series motherboards to fix the “UNSUPPORTED_PROCESSOR” problem (Sept. 6):–UNSUPPORTED-PROCESSOR–caused-BSOD-on-MSI-s-Intel-700-and-600-Series-Motherboards-142277

  14. Raphael Benzo said on September 24, 2023 at 9:52 pm

    I try to disable the Diagnostics Tracking Service (Connected Devices Platform User Services) but it wont let me disable it, any help will be greatly appreciated.
    Tank you for your help

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