How can I handle CONNECTED and DISCONNECTED events?

[Weedy]

On 18 December 2016 at 20:10, Son Tran <samtron1412 at gmail.com> wrote:
> Hello!
>
> I am using wpa_supplicant to connect to wireless networks. Now, I want to
> use OpenVPN to connect to my VPN, and I want to start OpenVPN service
> when wpa_supplicant connects to a network and stop OpenVPN service when
> wpa_supplicant disconnects to a network. How can I solve this problem? I
> use systemd to start wpa_supplicant at boot.

https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/
Sound like googling network-online.target and VPN should get you somewhere.
I don't use systemd.