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

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

  1. We'll assume that you have already installed OpenResty and we won't cover that here. You will also need a paid subscription to the Security plan. Subscribe now!
  2. In the command line, run the command below to install the dependency using opm if you don't have it installed.
    Bash 
    
sudo opm get ledgetech/lua-resty-http
  3. Save the below code into a file called test.conf on your computer.
    Nginx 
    
worker_processes  1;
error_log logs/error.log;
events {
    worker_connections 1024;
}
http {
    resolver 8.8.8.8 ipv6=off;
    server {
        listen 8080 reuseport;
        location / {
            default_type text/html;
            content_by_lua_block {
                local cjson = require("cjson")

                local key = "YOUR_API_KEY"
                local ip = "8.8.8.8"
                local httpc = require("resty.http").new()

                local jsonstr = ""
                local code = 0
                local myhost = "api.ip2location.io"

                params = {
                    format = "json",
                    key = key,
                    ip = ip,
                }

                local ok, err, ssl_session = httpc:connect({
                    scheme = "http",
                    host = myhost,
                    port = 80,
                })
                if not ok then
                    ngx.log(ngx.ERR, "connection failed: ", err)
                    return
                end

                local res, err = httpc:request({
                    path = "/",
                    query = params,
                    headers = {
                        ["Host"] = myhost,
                    },
                })
                if not res then
                    ngx.log(ngx.ERR, "request failed: ", err)
                    return
                end

                local reader = res.body_reader
                local buffer_size = 8192
                code = res.status

                repeat
                    local buffer, err = reader(buffer_size)
                    if err then
                        ngx.log(ngx.ERR, err)
                        return
                    end

                    if buffer then
                        jsonstr = jsonstr .. buffer
                    end
                until not buffer

                local trailer = res:read_trailers()

                if trailer then
                    jsonstr = jsonstr .. trailer
                end

                local ok, err = httpc:set_keepalive()
                if not ok then
                    ngx.say("failed to set keepalive: ", err)
                    return
                end

                if code == 200 then
                    local result = cjson.decode(jsonstr)
                    if result["proxy"] ~= nil then
                        if result.proxy.is_vpn then
                            ngx.say("The IP " .. ip .. " is a VPN.")
                        else
                            ngx.say("The IP " .. ip .. " is NOT a VPN.")
                        end
                    else
                        ngx.say("ERROR: The is_vpn field requires a paid subscription to the Security plan.")
                    end
                elseif code == 400 or code == 401 then
                    local result = cjson.decode(jsonstr)
                    if result["error"] ~= nil then
                        ngx.say("ERROR: " .. result.error.error_message)
                    else
                        ngx.say(jsonstr)
                    end
                else
                    ngx.say("ERROR: Unable to connect to API.")
                end
            }
        }
    }
}
  4. In the command line, run the below command to export the path to the Nginx that is bundled with OpenResty. Modify the path if yours is different. If you have the normal Nginx service installed, make sure it is stopped.
    Bash 
    
export PATH=/usr/local/openresty/nginx/sbin:$PATH
  5. In the command line, run the below commands to start the Nginx and run the test code.
    Bash 
    
nginx -p `pwd`/ -c test.conf
curl http://localhost:8080/

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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