Debian - auto configure proxy when Network Manager connects an interface

using-bash_80proxy.sh

#!/bin/bash

## see: http://github.com/frgomes/debian-bin/blob/master/bash_80proxy.sh
SCRIPT=/home/rgomes/bin/bash_80proxy.sh

## INTF is the network interface, either a wired one, wireless or any other type
INTF=enp8s0

## DEFAULT_PROXY contains the HTTP_PROXY to be defined when INTF is connected
DEFAULT_PROXY=http://127.0.0.1:3128/

if [ "$1" == $INTF ] ;then
  source $SCRIPT
  case "$2" in
    up)
      if [[ $( netstat -an | fgrep :3128 ) ]] ;then
        unbound_local_zones_ifnet $INTF && sudo service unbound restart
        proxy_on $DEFAULT_PROXY
      else
        unbound_local_zones && sudo service unbound restart
        proxy_off
      fi
      ;;
    down)
      unbound_local_zones && sudo service unbound restart
      proxy_off             
      ;;
  esac
fi

Suppose you have a wireless connection with SSID called OpenWRT-5G.
In this supposed scenario, perform the following steps:

1. Download this script onto /etc/NetworkManager/dispatcher.d so that it matches your SSID name;
2. Adjust variable INTF so that it matches the name of your wireless interface;
3. Adjust variable DEFAULT_PROXY so that it matches your network environment.
4. Double check the logic of the up event, adapting it to your needs.