Charles D. Cranor, AT&T Labs--Research; Theo de Raadt, The OpenBSD Project Anonymous CVS is an advanced source file distribution mechanism we created to allow open source software projects to distribute source code and information about code to Internet users. Built on top of the Concurrent Versions System (CVS) revision control system, Anonymous CVS safely allows anonymous read-only access to a CVS source repository. Prior to the introduction of Anonymous CVS, access to a CVS repository had to be restricted to a select group of privileged software developers. The advantage of open source software is that it promotes reliability and quality by allowing independent peer review and rapid evolution of source code. By introducing Anonymous CVS, we have extended the concept of open source software projects to open source repository projects. Having an open source repository allows users to take a more active role in the debugging and development of open source projects. In this paper we will examine and compare the mechanisms used by open source projects to distribute source code. We will present the design and implementation of the first Anonymous CVS server (used to distribute the OpenBSD operating system). We will explain some of our concerns (e.g., security) and some of the problems wewhen trying to adapt CVS for anonymous use. We also will present other more recent source file distribution mechanisms that make use of an open CVS repository. Anonymous CVS is currently bring used by a number of projects including OpenBSD, FreeBSD, Mozilla, Ecgs, Gnome, Python, and GNUstep View the full text of this paper in PDF form and PostScript form If you need the latest Adobe Acrobat Reader, you can download it from Adobe's site To become a USENIX Member, please see our Membership Information.