I am looking for a way to block messaging apps installed on PCs running Debian. Specifically, Signal, Telegram, WhatsApp, and generic video game messaging. I am using Openwrt One, and all the machines to be blocked are on the local network connected to One. I have installed and correctly configured Adguard Home.
I am aware of the complexity of the task, which is very high for me as a beginner. If I understand correctly, the solution is to block certain ports. Can anyone recommend a starting point for approaching this issue correctly? The documentation I have found on the internet is either too generic or too advanced. I need something step-by-step. Any suggestions are welcome. Thank you.
First try to limit on device user permissions. Newer GNOME has parental controls built in, no idea how comprehensive it is. Parental Control on ArchWiki
Blocking ports usually isn’t possible as HTTPS is ubiquitous nowadays.
Use AdGuard Home to block DNS resolution.
If the apps fallback to raw IP access, try to find the IP ranges and block them with the firewall.