History and Acknowledgements

Where we came from.

Research Paper

Our research paper on Censys—A Search Engine Backed by Internet-Wide Scanning—appeared at the 22nd ACM Conference on Computer and Communications Security (CCS) in October 2015. The paper contains a full description of Censys's orginal architecture and several use cases.

research paper

A Search Engine Backed by Internet-Wide Scanning

Zakir Durumeric, David Adrian, Ariana Mirian, Michael Bailey, J. Alex Halderman
22nd ACM Conference on Computer and Communications Security (CCS'15)

Fast Internet-wide scanning has opened new avenues for security research, ranging from uncovering widespread vulnerabilities in random number generators to tracking the evolving impact of Heartbleed. However, this technique still requires significant effort: even simple questions, such as, "What models of embedded devices prefer CBC ciphers?", require developing an application scanner, manually identifying and tagging devices, negotiating with network administrators, and responding to abuse complaints. In this paper, we introduce Censys, a public search engine and data processing facility backed by data collected from ongoing Internet-wide scans. Designed to help researchers answer security-related questions, Censys supports full-text searches on protocol banners and querying a wide range of derived fields (e.g., 443.https.cipher). It can identify specific vulnerable devices and networks and generate statistical reports on broad usage patterns and trends. Censys returns these results in sub-second time, dramatically reducing the effort of understanding the hosts that comprise the Internet. We present the search engine architecture and experimentally evaluate its performance. We also explore Censys's applications and show how recent questions become simple to answer.


We ask that any publications that use data from Censys cite the service. If you're writing a blog post, feel free to just link to Censys. If you are writing an academic paper, please cite the following:

        author = {Zakir Durumeric and David Adrian and Ariana Mirian and Michael Bailey and J. Alex Halderman},
        title = {A Search Engine Backed by {I}nternet-Wide Scanning},
        booktitle = {Proceedings of the 22nd ACM Conference on Computer and Communications},
        month = oct,
        year = 2015


We are extremely grateful to Google, who graciously provided much of the infrastructure in the early days of Censys.

We thank Michael Bailey, Matthew Bernhard, Ben Burgess, Alishah Chator, Harsha Gotur, Ariana Mirian, Drew Springall, Benjamin VanderSloot, and Eric Wustrow for their help building and maintaining Censys. We also thank Elie Bursztein, Brad Campbell, Aleksander Durumeric, James Kasten, Kyle Lady, Adam Langley, HD Moore, Pat Pannuto, Vern Paxson, Paul Pearce, Niels Provos, Mark Schloesser, and the many contributors to the ZMap, ZGrab, and ZTag open source projects.

We further thank the exceptional staff at the University of Michigan and Merit Network for their help and support, including Jack Bernard, Chris Brenner, Kevin Cheek, Laura Fink, Michalis Kallitsis, Dan Maletta, Jeff Richardson, Donald Welch, and Don Winsor.

Routing information is provided by Merit Network and Team Cymru.