Analyzing performance using tcpdump
In this recipe, we will analyze the performance of an OpenVPN setup using the tcpdump utility. It is also possible to use the Wireshark utility, which is available for Linux, Windows, and Mac OS X. While this recipe does not cover any new OpenVPN functionality, it is useful to show how such an analysis can be made.
Getting ready
We use the following network layout:
Set up the client and server certificates using the Setting up the public and private keys recipe from Chapter 2, Client-server IP-only Networks. For this recipe, the server computer was running CentOS 6 Linux and OpenVPN 2.3.11. The client was running Fedora 22 Linux and OpenVPN 2.3.11. Keep the configuration file example8-8-server.conf from the Tuning UDP-based connections recipe from Chapter 2, Client-server IP-only Networks, as well as the client configuration, example8-8-client.conf, from the same recipe.
How to do it...
Start the server:
   [root@server]# openvpn --config example8-8-server...
