you can use the regex pattern (?i)vpn to block domains containing "vpn" in a case-insensitive manner. Here’s how to add it to Pi-hole:

1. Via Pi-hole Admin Interface:

1. Open the Pi-hole admin panel:

   • http://pi.hole/admin or http://<Your-Pi-hole-IP>/admin

2. Go to "Group Management" > "Domain Lists" > "Blacklist".

3. Click on the "Regular Expression" tab.

4. Add the following regex rule:

   (?i)vpn
   

5. Click "Add", then restart Pi-hole's DNS service:

   pihole restartdns

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2. Via Command Line (SSH):

If you prefer using the command line, SSH into your Pi-hole device and run:

pihole --regex '(?i)vpn'

This will add the regex to block any domain containing "vpn" (case-insensitive).

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3. Verification:

You can check if a domain is blocked by running:

pihole -q vpnexample.com

If blocked, it will show up in the query logs.