There are many packages around for different operating system environments, including OpenSSL (multi-platform) and Keychain Assistant (part of OS X.) For the purposes of this guide we will use SimpleAuthority, a GUI -driven application which is available for Linux, Windows and OS X. The software is free for up to 4 users, $50 for up to 50 users, and $860 for 50 or more users.
Software that issues certificates needs to be secure, so it is highly recommended you install SimpleAuthority on a dedicated server. Once SimpleAuthority has been installed, the first thing you’ll be asked to do before you can issue any certificates is create a new Certificate Authority.