Synology connect to a VPN in command line

Connecting to your VPN openSSH, PPTP or L2TP using the WebMan web page is pretty easy, just click on connect and tick the option "reconnect automatically". But the connection may be unstable and you may loose the connection. The reconnection may failed and the status of the VPN will stay in pending for connection. That's why you may want to use a script to check the status of the connection and reconnect to you VPN. To be able to do it in command line or in a script, Synology needs a flag using a file called vpnc_connecting to launch the connection otherwise, it won't work. This file has to be place in the directory /usr/syno/etc/synovpnclient/