Thanks to Kit Baum, my checkipaddresses is available from SSC.

checkipaddresses queries an IP address verification service (https://iphub.info/) that returns the information on IP addresses, including the internet service provider (ISP) and whether it is likely a server farm being used to disguise a respondent’s location.

checkipaddresses takes a list of IP addresses from the current dataset, checks them against IPHub, and creates a dataset (specified with using) with the information it returns. This dataset includes the ip (used for merging), country code, country name, ASN, ISP, block, and hostname. Especially important in this is the variable "block", which gives a score indicating whether the IP address is likely from a server farm and therefore should be excluded from the data.

For more background on the issue of fraudulent survey respondents and how to deal with them, see

Burleigh, Tyler, Ryan Kennedy, and Scott Clifford. 2019. "How to Screen Out VPS and International Respondents Using Qualtrics: A Protocol (October 12, 2018)." Available at SSRN: https://ssrn.com/abstract=3265459

Kennedy, Ryan, Scott Clifford, Tyler Burleigh, Ryan Jewell, and Philip Waggoner. 2018. "The Shape of and Solutions to the MTurk Quality Crisis." Available at SSRN: https://papers.ssrn.com/sol3/papers....act_id=3272468