Vpn Clients and /etc/resolv.conf

If Ivanti Secure Access Client (former Pulse Secure Client) makes you mad by changing your /etc/resolv.conf you are not alone.

A script on NetworkManager Dispatcher, with some resolvectl commands come handy.

Just create a script as /etc/NetworkManager/dispatcher.d/99-fixDNS, with something like:

#!/bin/bash -e

[[ "${DEVICE_IFACE:-dummy}" = "tun0" ]] && [[ "${NM_DISPATCHER_ACTION:-dummy}" = "up" ]] && {
    resolvectl dns tun0 10.10.10.10
    resolvectl domain tun0 ~example.com ~example.org
} 

Much more settings can be added, but now you have an idea how to solve it.