Optimizing performance using 'iperf'

This recipe is not really about OpenVPN but more about how to use the network performance measurement tool iperf in an OpenVPN setup. The iperf utility can be downloaded from http://sourceforge.net/projects/iperf/ for Linux, Windows, and MacOS.

In this recipe, we will run iperf outside of OpenVPN and over the VPN tunnel itself, after which the differences in performance will be explained.

Getting ready

We use the following network layout:

Install OpenVPN 2.0 or higher on two computers. Make sure the computers are connected over a network. Set up the client and server certificates using the first recipe from Chapter 2, Client-server IP-only Networks. For this recipe, the server computer was running CentOS 5 Linux and OpenVPN 2.1.1. The client was running Fedora 13 Linux and OpenVPN 2.1.1. Keep the configuration file basic-udp-server.conf from the Chapter 2 recipe Server-side routing at hand, as well as the client configuration file basic-udp-client.conf from...