--> If they only want this thing to happen when root logs in directly on a console or ssh, then .profile may indeed be the correct answer.
Yes,I don't need to run xorg and a desktop environment,since warp-cli disconnect and warp-cli connect do not require them.
I wouldn't to login as root automatically,but I've realized that this command :
echo 1 > /proc/sys/net/ipv4/ip_forward
work only if I'm root. It does not work using sudo. So,in the end I've chosen to be root instead of a normal user that can use sudo.
Mario.