Disable MDNS in Chrome via Chrome policies on the commandline

disable-mdns-chrome.sh

#!/bin/bash
#
# This assumes you are using "Chrome" from the official Google site via the .deb or .rpm
# This may or may not work with your distributions "Chromium" or "Chrome" package!
# 
# Run this script then restart Chrome, you will see it is no longer bound to UDP:5353
#
mkdir -p /etc/opt/chrome/policies/{managed,recommended} || echo FAIL, ARE YOU ROOT
chmod go-w /etc/opt/chrome/policies/managed || echo FAIL, ARE YOU ROOT
cat > /etc/opt/chrome/policies/managed/managed_policy.json << 'EOF'
{ "EnableMediaRouter": false }
EOF

#
# UPDATE: Unfortunately, there is another option that must be set as of latest versions of Chrome
# stable. It can not be set in the policy file but must be set manually in chrome://flags. Without
# this additional change, Chrome will still spam IGMP group requests on all interfaces at boot-time
#
# The flag is: #enable-webrtc-hide-local-ips-with-mdns
# It must be set to 'Disabled'
#

You can try setting the immutable flag on the configuration file after you modify it. You’ll need elevated privileges to do so, though

The simplest way to do a basic test would be to shut down all chrome instances, make the change, then sudo chattr +i . Until you chattr -i the file, it won’t be mutable by any users (not even root)

The file has to be on an ext-based file system because it uses the extfs extended attributes

You could also try just chowning it to root, but it’s possible it could be deleted and recreated as a normal user since the directory will be owned by a normal user

good luck, let me know if you figure anything out. I stopped using Chrome entirely a while ago so haven’t looked at it all on probably over a year

BTW- there are probably extensions that can disable the mDNS- but a pure configuration change is so much better than adding more code to your system- even if it is (mostly) sandboxed