How can I use an API to detect if an IP address is a VPN in Erlang?

To detect if an IP address is a VPN using IP2Location.io in Erlang, you can use the IP2Location.io API to retrieve geolocation and related data.

  1. We'll assume that you have already installed Erlang and we won't cover that here. You will also need a paid subscription to the Security plan. Subscribe now!
  2. Our example is for the Debian operating system. So, we'll be installing the erlang-jiffy Debian package for parsing the JSON results. For other platforms, please refer to the Jiffy GitHub.
  3. In the command line, run the command below to install the erlang-jiffy package if you don't have it installed.
    Bash 
    
sudo apt install erlang-jiffy
  4. Save the below code into a file called test.erl on your computer.
    Erlang 
    
-module(test).
-export([runtest/0]).

runtest() ->
	Key = "YOUR_API_KEY",
	IP = "8.8.8.8",

	ssl:start(),
	inets:start(),
	
	MyParams = uri_string:compose_query([{"format", "json"}, {"key", Key}, {"ip", IP}]),
	case httpc:request(get, {"https://api.ip2location.io/?" ++ MyParams, []}, [{ssl, [{versions, ['tlsv1.2']}]}, {autoredirect, false}], []) of
		{ok, {{_, 200, _}, _, Body}} ->
			Result = jiffy:decode(unicode:characters_to_binary(Body,unicode,utf8),[return_maps]),
			case maps:is_key(<<"proxy">>, Result) of
				true ->
					Proxy = maps:get(<<"proxy">>, Result),
					IsVpn = maps:get(<<"is_vpn">>, Proxy),
					case IsVpn of
						true ->
							io:format("The IP ~s is a VPN.~n", [IP]);
						_ ->
							io:format("The IP ~s is NOT a VPN.~n", [IP])
					end;
				_ ->
					io:format("ERROR: The is_vpn field requires a paid subscription to the Security plan.~n", [])
			end;
		{ok, {{_, 400, _}, _, Body}} ->
			Result = jiffy:decode(unicode:characters_to_binary(Body,unicode,utf8),[return_maps]),
			case maps:is_key(<<"error">>, Result) of
				true ->
					Error = maps:get(<<"error">>, Result),
					io:format("ERROR: ~s~n", [maps:get(<<"error_message">>, Error)]);
				_ ->
					io:format("ERROR: ~p~n", [Result])
			end;
		{ok, {{_, 401, _}, _, Body}} ->
			Result = jiffy:decode(unicode:characters_to_binary(Body,unicode,utf8),[return_maps]),
			case maps:is_key(<<"error">>, Result) of
				true ->
					Error = maps:get(<<"error">>, Result),
					io:format("ERROR: ~s~n", [maps:get(<<"error_message">>, Error)]);
				_ ->
					io:format("ERROR: ~p~n", [Result])
			end;
		{error, Reason} ->
			io:format("ERROR ~p~n", [Reason])
	end.
  5. In the command line, run the below command to launch the Erlang shell.
    Bash 
    
erl
  6. Inside the Erlang shell, run the below commands to compile and run the test code.
    Erlang 
    
c(test).
test:runtest().

This script will check if the specified IP address is a VPN. Make sure to replace 8.8.8.8 with the IP address you want and replace YOUR_API_KEY to your own API key.

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