OpenVPN and systemd
===================

As of OpenVPN v2.4, upstream is shipping systemd unit files to provide a
fine grained control of each OpenVPN configuration as well as trying to
restrict the capabilities the OpenVPN process have on a system.


Configuration profile types
---------------------------
These new unit files separates between client and server profiles.  The
configuration files are kept in separate directories, to provide clarity
of the profile they run under.

Typically the client profile cannot bind to any ports below port 1024
and the client configuration is always started with --nobind.

The server profile is allowed to bind to any ports.  In addition it enables
a client status file, usually found in the /run/openvpn-server directory.
The status format is set to version 2 by default.  These settings may be
overridden by adding --status and/or --status-version in the OpenVPN
configuration file.

Neither of these profiles makes use of PID files, but OpenVPN reports back to
systemd its PID once it has initialized.

For configuration using a peer-to-peer mode (not using --mode server on one
of the sides) it is recommended to use the client profile.


Configuration files
-------------------
These new unit files expects client configuration files to be made available
in /etc/openvpn/client.  Similar for the server configurations, it is expected
to be found in /etc/openvpn/server.  The configuration files must have a .conf
file extension.


Managing VPN tunnels
--------------------
Use the normal systemctl tool to start, stop VPN tunnels, as well as enable
and disable tunnels at boot time.  The syntax is:

 - client configurations:
    # systemctl $OPER openvpn-client@$CONFIGNAME

 - server configurations:
    # systemctl $OPER openvpn-server@$CONFIGNAME

Similarly, to view the OpenVPN journal log use a similar syntax:

   # journalctl -u openvpn-client@$CONFIGNAME
 or
   # journalctl -u openvpn-server@$CONFIGNAME

* Examples
  Say your server configuration is /etc/openvpn/server/tun0.conf, you
  start this VPN service like this:

    # systemctl start openvpn-server@tun0

  A client configuration file in /etc/openvpn/client/corpvpn.conf is
  started like this:

    # systemctl start openvpn-client@corpvpn

  To view the server configuration's journal only listing entries from
  yesterday and until today:

    # journalctl --since yesterday -u openvpn-server@tun0