Apache is a free and open-source cross-platform web server software.
FreeBSD is a free and open-source Unix-like operating system.
OpenSSL is a software library for applications that secure communications over computer networks against eavesdropping or need to identify the party at the other end.
PHP is a general-purpose scripting language used for web development.
SquirrelMail is an open-source web-mail package that is based on PHP language. It provides a web-based-email client and a proxy server for IMAP protocol.