Cipher mismatches

In this recipe, we will change the cryptographic ciphers that OpenVPN uses. Initially, we will change the cipher only on the client side, which will cause the initialization of the VPN connection to fail. The primary purpose of this recipe is to show the error messages that appear, not to explore the different types of ciphers that OpenVPN supports.

Getting ready

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 6 Linux and OpenVPN 2.3.11, and the client was running Windows 7 64 bit and OpenVPN 2.3.10. Keep the configuration file, basic-udp-server.conf, from the Server-side routing recipe from Chapter 2, Client-server IP-only Networks, as well as the client configuration file, basic-udp-client.conf.

How to do it...

1. Start the server using the configuration file, basic-udp-server.conf:

           [root@server]# openvpn --config basic-udp-server.conf
   

2. Next, create...