Install OpenVPN 2.0 or higher on two computers. Make sure the computers are connected over a network. For this recipe, the server computer was running CentOS 5 Linux and OpenVPN 2.1.1 and the client was running Windows XP SP3 and OpenVPN 2.1.1 In this recipe we'll use the secret.key file from the OpenVPN Secret keys recipe.

The connection is established:

The command-line and the configuration file are read and parsed from left to right. This means that most options that are specified before the configuration file can be overruled by entries in that file. Similarly, options specified after the following directive overrule the entries in that file:

--config client.conf

Hence, the following option overruled the line 'port 1194' from the configuration file:

--port 11000

However, some options can be specified multiple times, in which case the first occurrence "wins". In that case, it is also possible to specify the option before specifying the --config directive.

Here is another example to show the importance of the ordering of the command-line parameters:

C:\>"\Program Files\OpenVPN\bin\openvpn.exe" \
    --verb 0 \
    --config client.conf \
    --port 11000

This produces the exact same connection log as shown before. The 'verb 3' from the client.conf configuration file overruled the --verb 0 as specified on the command line. However, with the following command line:

C:\>"\Program Files\OpenVPN\bin\openvpn.exe" \
    --config client.conf \
    --port 11000 \
    --verb 0

Then the connection log shows the following:

… NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables

This shows all the other messages that have been muted.