Rules to block Windows spy / telemetry
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WindowsSpyBlocker is a set of rules to block Windows spy / telemetry based on multiple tools to capture traffic.
It is open for everyone and if you want to contribute, take a look at the Wiki.
Do not forget to star 🌟 the project if you like it 😍

How ?

I use QEMU virtual machines on the server virtualization management platform Proxmox VE based on :

  • Windows 10 Pro 64bits with automatic updates enabled.
  • Windows 8.1 Pro 64bits with automatic updates enabled.
  • Windows 7 SP1 Pro 64bits with automatic updates enabled.

I clean traffic dumps every day and compare results with the current rules to add / remove some hosts or firewall rules.

Tools used to capture traffic :

All traffic events are available in the logs folder.



data is the master folder of this project. It contains the blocking rules based on domain names or IPs addresses detected during the capture process.

  • data/<type>/winX/spy.txt : Block Windows Spy / Telemetry
  • data/<type>/winX/update.txt : Block Windows Update
  • data/<type>/winX/extra.txt : Block third party applications


Copy / paste the content of the files in data/hosts in your Windows hosts file located in C:\Windows\System32\drivers\etc\hosts.

You can use the HostsMan freeware to keep update your hosts file.
I have created a git hook to publish the hosts files to my personal website :

Windows 7
Windows 8.1
Windows 10


Some queries use IP addresses but you can stop them with your Firewall.
All relative information about these IP addresses are listed in the CSV files firewall- in the logs folder.
To add / remove firewall rules or test IPs, read the instructions in scripts/firewall folder.

NCSI (Network Connectivity Status Indicator)

Windows check a Microsoft site for connectivity, using the Network Connectivity Status Indicator site.
NCSI performs a DNS lookup on and sends a DNS lookup request for
You can block this probe by adding the content of the data/<type>/winX/extra.txt hosts file.

But you will have a "No Internet access" warning in your system tray.
To solve this problem you can use the alternative WindowsSpyBlocker NCSI. Read the instructions in scripts/ncsi folder.


DNSCrypt is a protocol for securing communications between a client and a DNS resolver. With this tool you can blacklist some domains with the plugin libdcplugin_example_ldns_blocking and add domains with leading and trailing wildcards.
To install DNSCrypt on Windows, read the README-WINDOWS on the official GitHub repository.
Copy the content of the dnscrypt files in the repository in a file called for example C:\blacklisted-domains.txt and enter this command :

dnscrypt-proxy -R <name> --plugin=libdcplugin_example_ldns_blocking.dll,--domains=C:\blacklisted-domains.txt

Replace <name> with a public DNS resolvers supporting DNSCrypt you want to use. Note its name, in the first column (for example:


Some hosts are not blocked and required a top level application.
For example you can use Proxifier software to block Microsoft spy.
Copy the content of the proxifier files in data/proxifier in a blocked rule :


DNS/IP block rules using dnsmasq / iptables are available in data/openwrt folder.
These rules are focused on latest OpenWrt release (Chaos Calmer 15.05.1).

Requires package "iptables-mod-nat-extra" for port 53 (DNS) redirect rule from dnsmasq.conf.
dnsmasq.conf is bypassed if you use DNSCrypt on client machine (recommended) so use hosts before DNSCrypt exit point.

DNSCrypt is also available in OpenWrt repo, but may be slow and CPU hungry on average routers, stay with the PC client as recommended.


Logs of tools used to capture traffic and resolution of firewall rules in CSV format available in the logs folder.

  • *-all.csv : all events
  • *-hosts-count.csv : number of events per host
  • *-unique.csv : first trigger of an event per host / process / destination port


Several scripts are used to ease implementation of rules and contribution. To use these scripts you have to download and install the Visual C++ Redistributable for Visual Studio 2012 (vcredist_x86.exe).

  • diff.bat : Generate a diff log based on CSV logs and data for Sysmon, Proxifier and Wireshark.
  • firewall.bat : Add / remove rules and resolve IPs adresses
  • ncsi.bat : Apply an alternate NCSI and test your internet connection the Microsoft way. More info...
  • proxifier.bat : Extract events from log and generate CSV files. More info...
  • sysmon.bat : Install / uninstall Sysmon and extract events log then generate CSV files. More info...
  • wireshark.bat : Extract events log then generate CSV files based on IPv4 hosts. More info...

Projects using WindowsSpyBlocker

  • pi-hole : A black hole for Internet advertisements (designed for Raspberry Pi).
  • StopAd : Service for MikroTik routers made to block "advertising" and more.
  • OpenWrt adblock package : DNS based ad/abuse domain blocking
  • Unified hosts file : Extending and consolidating hosts files from a variety of sources.
  • FreeContributor : Simple DNS Ad Blocker.


  • Create a desktop app
  • Resolve service name from svchost.exe PID
  • Reproduce steps on virtual machine to invoke spy IPs (native apps, win update, explorer, etc...)
  • Manage geoloc
  • Create script to update hosts easily


MIT. See LICENSE for more details.
Icon credit to Icons8.