MicroHOWTO - NetworkManager controlled OpenVPN connections

setup-vpn.sh

#!/bin/bash
# {MicroHOWTO|Script} to setup a NetworkManager controlled openvpn connection

# OVPN Config file is the parameter to the script (no checks, blind faith) 
OVPN_CONF="$1"

# Install the requirements if not available
# SUDO REQUIRED
sudo apt install -y openvpn network-manager-openvpn # Debian 10/*buntu 20.04 and later 
# yum -y install openvpn NetworkManager-openvpn # RHEL 7/Rocky 7/Fedora ?? and later

# Import connection into NetworkManager
# SUDO NOT REQUIRED: Well thought out implementation of NM
nmcli connection import type openvpn file "${OVPN_CONF}"

# Fix the problem of VPN adding it's default routes at higher priority 
# than default route of underlying local network (and thus breaking network access) 
nmcli con modify "${OVPN_CONF//.ovpn}" ipv4.never-default true
nmcli con modify "${OVPN_CONF//.ovpn}" ipv6.never-default true

# Fix issue with interface not asking for username
USER="$(grep -Eh '^\s+Subject:.* CN=' "${OVPN_CONF}" | sed 's#.* CN=\([^,/]\+\)#\1#g')"
nmcli con modify "${OVPN_CONF//.ovpn}" vpn.user-name "$USER"

# Show the connection info
nmcli con show "${OVPN_CONF//.ovpn}"

# Use NetworkManager UI applet to start VPN
echo "Use the Network applet of your UI to control ${OVPN_CONF//.ovpn} VPN start/stop as per your requirements."