[arin-tech-discuss] matching ip addresses to owners of a domain

David Huberman dhuberma at arin.net
Mon Mar 12 17:14:56 EDT 2012


If you have a domain name, you can use our API to discover IP address
registrations ("NETs") associated with POCs who have registered email
addresses in that domain name. There are probably a number of ways to get
from here to there, but here's one solution I came up with:

1) Paragraph 4.4.2 of the document:


... describes the use of matrix parameters. What we're interested in this
first step is to discover a list of POCs who have email addresses in the
given domain name. If our domain name is washgas.com, for example, we can


We get one match, an Ed Rudy from Washington Gas, and it shows us his POC
handle is ERU10-ARIN.

2a) From there, we can search up the hierarchy and ask the API: show me
all organization records ("ORGs") associated with these POCs, so that I
can find NETs that are registered to the ORGs. Why do we ask this? Because
ARIN's Whois is a relational database. NETs are registered to ORGs. ORGs
have POCs who serve various roles (admin, tech, abuse, NOC). So to get to
the NET from the POCs, we have to go via the ORG.

Paragraph 4.4.1 of the documentation shows us how to search for
referential data.  Using our example, we take ERU10-ARIN and ask for all
ORGs it's associated with:


The resulting list has 4 matches, but only 1 unique match: WGL-23, the ORG
defining Washington Gas.

2b) Now we can search for the NETs associated with each of the unique
matches. Using the same methodology, we search for NET data referencing
the ORG. Witness:


The resulting list has 1 IP address registration: NET-208-76-232-0-1

So we can take that and GET:


.. to programatically discover the starting and ending addresses and/or
the CIDR.

3) Finally, to be complete in our queries, we should search for all NETs
directly associated with these POCs.  That way we capture any NETs that
the POC is a contact on, but for which the POC is not a contact on the
ORG. Using our example one more time:


There aren't any matches for ERU10-ARIN, and for most POCs, this result
set will be empty.  But to get a complete picture, you would want to
perform this search anyway.

Hope this answer is helpful for you!


David R Huberman
Principal Technical Analyst, ARIN

On 3/12/12 3:39 PM, "Karl Baum" <karl.baum at gmail.com> wrote:

I am trying to use the arin api to match ip addresses of our users to
certain companies within our database.  For each company I only have a
name and domain.  Can i use Arin to associate an ip address with one of
the company domains stored within our database?


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