Welcome to: bttf-whois.measurement.network

Welcome. This site provides a service for looking up historic announcement information for IPv4 and IPv6 addresses.

single usage: whois -h bttf-whois.measurement.network " 20220123" # Date is YYYYMMDD

bulk usage: cat infile | nc bttf-whois.measurement.network 43 > outfile

infile format:

begin 20220123 20110928 20220123

output description:

  # Requested IPv4 or IPv6 address
  "IP": "",
  # Date for which data was requested
  "QDATE": "20210101",
  "results": {
    # First time the most specific prefix for address has been seen
    # first with this specific set of announcing ASes
    "DATA_FIRST": 20180320,
    # Last time this entry was seen, i.e., valid until. If it is
    # null, the most specific is still visible in the most recent
    # dataset (valid NOW).
    "DATA_LAST": null,
    # List of ASNs that announced the most specific prefix for the
    # requested address.
    "asns": [
    # The most specific matching prefix from the dataset.
    "prefix": "",
    # AS2ORG mappings for all announcing ASN.
    "as2org": [
        # AS number
        "ASN": 13335,
        # AS name
        # RIR that is the data source in the AS2ORG mappings
        "RIR": "RIPE",
        # Org objects associated with the ASN
        "orgs": [
            # Country code attributed to an organization
            "CC": "US",
            # RIRs that hold an instance of this ORG object
            "RIR": "ARIN,RIPE",
            # Organization name from the ORG object
            "ASORG": "Cloudflare Inc"


Q: What does this do?
A: This system lets you check who announced an IP address or prefix in the past; Daily granularity, as far back as 2006.

Q: But... why?!
A: So you can accurately bulk-attribute IP addresses to organizations when working with an old dataset.

Q: This all sounds really interesting. Where can i learn more?
A: Here: Streibelt et al., 'Back-to-the-Future Whois: An IP Address Attribution Service for Working with Historic Datasets', Passive and Active Measurement Conference, 2023.

Q: Who runs this service?
A: This site is operated by Tobias Fiebig, Campus E14, 66123 Saarbrücken, Germany, Email: contact@measurement.network.

Q: Do you have a privacy policy?
A: Yeah. Here: Logging is disabled, there are no cookies, and we only process data to provide this service (deliver this static HTML page and resolve your IP attribution requests). i.e., to provide this service (Art. 13 DSGVO). Everything this site processes which can be traced back to you is only ephemerally held in memory and not written to disk. You can't request deletion, correction, or a copy of your data, because there is no data. The data we use to attribute IP addresses to announcing organizations are a public dataset of routing and organizational information, as publicly provided bei CAIDA.