Scanning FAQ

What ports and protocols does Censys global scanning engine scan?

Please see Internet Scanning for a comprehensive list of the protocols and ports we scan.

How frequently does Censys global scanning engine scan the Internet?

Censys's global scanning engine continuously scans the Internet to find new services, remove old services, and refresh data about current services in its free searchable index.

Discovery scans are performed on several schedules based on the popularity of certain ports and networks (such as those allocated to cloud providers) in the IPv4 address space.

Every day, every known service in our host dataset is evaluated for its age, and any service older than 24 hours is rescanned to verify its accuracy.

How complete is the Censys host data set?

The Censys next-gen scan engine scan provides visibility for over 99% of the public Internet by all 65,535 ports using automatic service detection from multiple scanning perspectives.

The Censys datasets also have higher fidelity in terms of tracking changes to the Internet over time and providing the most accurate snapshot of the current Internet.

What third-party sources does Censys use to enrich Search data?

We provide geolocation data using the IPInfo Geolocation API and routing information using the RouteViews dataset.

What access does Censys provide for researchers?

We provide academic and other non-commercial researchers with free access to the same data as our highest-tiered customers: Censys datasets available in Google BigQuery and up-to-date raw scan data for downloading. This access is strictly limited to non-commercial use. Explore the details of research access.

Can I opt out of Censys global scanning engine scans?

Censys strives to be a good citizen of the security community. Our scans help the scientific community accurately study the Internet and help security practitioners defend it.

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Note

Censys conducts scans solely to gather information. It never attempts to log into services, access databases, or gain authenticated entry to any system.

If you want to opt-out, configure your firewall to drop traffic from the subnets we use for scanning.

We do not remove any results from Censys data sets, but if you block these subnets, your hosts are automatically pruned out of our daily snapshots.

What is the Censys relationship with the University of Michigan and Google?

Censys was originally an academic research project at the University of Michigan. From 2015 to 2017, It was operated in Michigan with generous support from the Google Anti-Abuse Team. During this time, our license restricted access to non-commercial research. Since then, we've spun out from the University of Michigan into an independent company.

What is the Censys relationship with the ZMap Project?

Censys was started by the same team that created ZMap, and the Censys legacy scanner used many of the ZMap tools to collect and annotate data. The ZMap Project is and will remain an independent open-source project and is primarily maintained by the Censys development team.

We are staunch supporters of open-source software.