Open source and peer production have been praised as organisational models that could change the world for the better. It is commonly asserted that almost any societal activity could benefit from distributed, bottom-up collaboration — by making societal interaction more open, more social, and more democratic. However, we also need to be mindful of the limits of these models. How could they function in environments hostile to openness? Security is a societal domain more prone to secrecy than any other, except perhaps for romantic love. In light of the destructive capacity of contemporary cyber attacks, how has the Internet survived without a comprehensive security infrastructure? Secrecy vs. openness describes the realities of Internet security production through the lenses of open source and peer production theories. The study offers a glimpse into the fascinating communities of technical experts, who played a pivotal role when the chips were down for the Internet after large-scale attacks. After an initial flirtation with openness in the early years, operational Internet security communities have put in place institutional mechanisms that have resulted in less open forms of social production.