My application's access to nominatim.openstreetmap.org is blocked: forbidden

Question

My original goal is it, to get nominatim access from a windows application, where users can search for places etc. We are doing this since many years quite well with other providers (with google, bing, mapquest etc.) and i wanted to add nominatim as well. This is a c++ application on windows using boost::asio for https / https access. https works well for all other services.

If I, instead, use wget, I get a "Unable to establish SSL connection." error (other question entry).

I did further inspections on access from my application. Indeed i get a "blocked" result:

Retrieving "nominatim.openstreetmap.org/search?q=,berlin,,&format=xml&polygon=1&addressdetails=1"
Connect HTTPS
HTTPS: Resolve OK
HTTPS: Connect OK
HTTPS: Verifying "/C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3"
HTTPS: Verifying "/CN=nominatim.openstreetmap.org"
HTTPS: Handshake OK; Request header: GET /search?q=,berlin,,&format=xml&polygon=1&addressdetails=1 HTTP/1.0^M
Host: nominatim.openstreetmap.org^M
Accept: */*^M
Connection: close^M
^M

HTTPS response
 Forbidden^M
Date: Thu, 29 Nov 2018 20:36:11 GMT^M
Server: Apache/2.4.29 (Ubuntu)^M
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload^M
Expect-CT: max-age=0, report-uri="https://openstreetmap.report-uri.com/r/d/ct/reportOnly"^M
Upgrade: h2^M
Connection: Upgrade, close^M
Last-Modified: Mon, 02 Jan 2017 21:56:07 GMT^M
ETag: "3a5-545239e6fbc4c"^M
Accept-Ranges: bytes^M
Content-Length: 933^M
Content-Type: text/html; charset=utf-8^M
^M
<html>
<head>
<title>Access blocked</title>
</head>

Why is this the case? I did not attempt any bulk requests. In total maybe some 10. Do i need a additional header field to my request?

Accepted Answer

Only 10 requests feels a bit strange to me, too - however, probably others have used the same library to access nominatim before you and may be using the same identification. Let me cite https://operations.osmfoundation.org/policies/nominatim/ : "Provide a valid HTTP Referer or User-Agent identifying the application (stock User-Agents as set by http libraries will not do)." You should set a custom HTTP User Agent and Referer for your application. Maybe simply its website (which would offer a possible way of contacting you in case the service operators see any problem).

My application's access to nominatim.openstreetmap.org is blocked: forbidden

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