Mars is a simple, extensible, services-oriented network status monitor written in Java. It monitors a network by simulating client connections to Internet services and reporting when those services are not responding as expected. It is quick and easy to install and configure, which distinguishes it from more complex network monitoring tools. Mars monitors HTTP, HTTPS, SMTP, IMAP, POP3, FTP, SSH, and JDBC, and notifies via SMTP and XMPP "out of the box". Support for new protocols, notifications, and reporting mechanisms is easy to add via Java or XML.