Cisco IPsec VPN Negotiation Fails After Network Disconnect On Mac OSX 10.11.3 (likely previous), the built-in Cisco IPsec VPN client will refuse to reconnect to the VPN server after a network failure (cable unplugged, wifi lost etc.)

After about 30 seconds of 'Connecting...' in the menu bar, an error pops up about 'Failure to negotiate'. Deleting the service and creating a new one does not fix the issue, but a reboot does. 



How do I reconnect to the server without having to reboot?
The problem is that racoon, Apple's proprietary Cisco VPN client doesn't close itself gracefully on disconnect, this actually makes all Cisco VPNs stop working if one was connected when the network failure occurred.

To fix this, simply stop racoon:


Open Terminal (/Applications/Utilities/Terminal)
Type sudo killall racoon (you will be asked for your password)


You may now quit Terminal and reconnect the VPN as normal.