The development version can be found in the check_openvpn-simple git repository. The latest official release is check_openvpn-simple-0.0.1.
A Nagios plugin for checking whether or not an OpenVPN server is alive.
We don't actually interact with the OpenVPN server; we merely send it a a magic (heretofore unexplained) byte sequence and ensure that we get some kind of response.
Note: If the server uses a TLS auth key, the plugin will only work if the server is running over TCP (the response will be empty but at least it will come, preventing a timeout). Over UDP, OpenVPN simply ignores the probe and we have no way of knowing whether or not a service is actually running on that port.
Perform a basic check using the default port and protocol:
user $ check_openvpn-simple vpn1.example.com
Check a server that runs on TCP/443 (this is used to sneak past firewalls that allow HTTPS but block other traffic):
user $ check_openvpn-simple --tcp --port 443 vpn2.example.com
Email them to me at firstname.lastname@example.org.