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Introduction

Existing approaches to IP geolocation chose to invent their own non-standard APIs. We feel that is notnecessary. DNSis a highly efficient way to export IP-to-<something> datasets. Ade facto standard for such dataset lookups already exists. Serving data via DNS, rather than a flat file,guarantees that answers to queries remain fresh.

With thecountry.netop.org service,NetOp demonstrateshere that no special APIs are needed. All you need is a standard DNSresolver API.

Using the service

NetOp runs a service that allows the public Internet to makeDNSBL-stylequeries for a given IPv4 address's ISO 3166 country code, as stored in aTXT RR. The domain toquery iscountry.netop.org, for example1.0.0.127.country.netop.org.

The server will return a TXT RR containing the two-letter ISO 3166country code. As Webnet77 data notes, there are some variances in thecountry code:

• AP - non-specific Asia-Pacific location
• CS - (Formerly Czechoslovakia) Czech Republic and Slovakia
• YU - (Formerly Yugoslavia) Serbia, Montenegro, etc.
• EU - non-specific European Union location
• FX - France, Metropolitan
• PS - Palestinian Territory, Occupied
• UK - United Kingdom (standard says GB)
• ZZ - IETF RESERVED address space.

You may alsoquery the service via asimple web form.

Application developers

This service is being provisioned such that it will exist in the longterm. I encourage application developers to use the country.netop.orgsub-domain in their geolocation applications. Although there are noexplicit traffic limits, heavy users should rungood DNS cache servers of their own or mirror the data themselves.

Nigel Gourlay createdIP::Country::DNSBL,a Perl module available viaCPAN.

Status

Public beta. It works, but with only one server, won't survive beingslashdotted, etc. See 'Future directions' below for more.

Words of caution

Returning address/prefix (CIDR), and caching the address block, isfar preferable to dealing with each individual IPv4 address.Although mitigated, this issue affects scaling, and will only becomemore acute as IPv6 support is added. Anybody know a good way to encode(address)->(country code,netblock) in a DNS request, such that, arequest for another address in the same netblock will return acached answer? Such an improvement would reduce service queriesexponentially.

Back end

We userbldnsd toserve the geolocation data. (not to be confused withdjb's daemon of a similar name)rbldnsd provides very user-friendly alternate zone formats, and makes iteasy to split a dataset across multiple files.Webnet77 provides the geolocation data, andOSUOSL provides the server colocation.

Future directions

IPv6 support needs doing.We are seeking slave servers for the country.netop.org sub-domain.Must be a stable node, on a stable IP, in a datacenter with backup power.Root access to a Virtual or dedicated server runningLinux strongly preferred.DNS data willbe updated nightly via HTTP or similar; That hasn't beenworked out yet. Visit thesponsors anddonations page if you would like to donate a server.