Managing an Openconnect VPN Connection with launchd on OSX
Openconnect is an open source implementation of the Cisco AnyConnect client. It provides easier installation on OSX, via Homebrew, and, and a command-line interface. In this article I investigate using launchd to manage the connection. This saves having to leave a terminal open with the connection running, or having to look up the PID if running in the background to kill the connection.
Openconnect requires sudo access, so I decided to configure the service as a system daemon. You could also configure the service as a user Agent and configure openconnct to have password-less sudo priviledges.
If your VPN server does not support certificates for authentication, as mine, you will have to save your password to a file. You can do this as follows:
sudo -e /etc/vpn_secret # enter your password, with no newlines sudo chmod og-rw /etc/vpn_secret # remove read/write access from all but root
I also ran into a hiccup: launchd ends processes by sending SIGTERM, which is meant to indicate that a program should end gracefully. Unfortunately, openconnect will only close gracefully on a SIGINT signal, and I cannot see a way to configure launchd to change the signal sent. To get around this, I wrote a wrapper to catch a SIGTERM and send a SIGINT to openconnect, saved as
Make sure this file has execute rights.
sudo chmod +x /etc/openconnect_wrapper
Finally, we can write the job definition to
/Library/LaunchDaemons/vpn.openconnect.plist, or in
/Library/LaunchAgents if you decided to use an agent.
__KEYS__ in the above with your specific requirements.
Now the connection can be started and stopped with
sudo launchctl start vpn.openconnect and
sudo launchctl stop vpn.openconnect.
launchctl start and
launchctl stop are deprecated. If anyone knows the correct way to start and stop these services, please let me know in the comments or via email.
I like to have a visual indicator when I am connected to VPN, and this is one thing I miss about Cisco AnyConnect. I have been playing with Ubersicht, so a desktop indicator could be helpful.