Proxy Detection Using ExtractIP Geolocation API with cURL

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Introduction

Detecting proxy usage is essential for applications that rely on accurate IP geolocation. In this guide, we'll demonstrate how to check for proxy usage by comparing two API requests to api.extractip.com/geolocate: one made directly and another routed through a proxy. We will also compare specific fields from the JSON responses to highlight differences.

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Prerequisites

• Access to the ExtractIP API (api.extractip.com/geolocate)
• Basic knowledge of the command line
• An available proxy server (IP and port)
• Tools like jq and diff (installed by default on many systems)

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Step-by-Step: Proxy Detection via cURL

1. Direct API Request (No Proxy)

First, send a direct request to your API to check the IP address from your machine:

curl -s "https://api.extractip.com/geolocate" > direct_response.json

Expected Response Example:

{
    "exit_ip": "8.8.8.8",
    "capital": "Washington",
    "country_code": "US",
    "country_name": "United States",
    "country_region": "North America",
    "country_neighbors": [
        "CA",
        "CU",
        "MX"
    ],
    "time_zone": "America/Los_Angeles",
    "domain_name": ".us",
    "domains": [
        "dns.google."
    ],
    "currency": "USD",
    "call_codes": [
        "+1"
    ],
    "flag_url": "https://api.extractip.com/flags/3x2/US.svg"
}

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2. API Request via Proxy

Next, route the request through a proxy server. Replace proxy_ip:proxy_port with your proxy details:

curl -s "https://api.extractip.com/geolocate" --proxy http://proxy_ip:proxy_port > proxy_response.json

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Comparing Results

Method 1: Using diff

To compare the entire responses:

diff direct_response.json proxy_response.json

This highlights differences line-by-line. For more concise output, use jq to format:

jq -S . direct_response.json > direct_sorted.json
jq -S . proxy_response.json > proxy_sorted.json
diff direct_sorted.json proxy_sorted.json

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Method 2: Comparing Specific Fields with jq

To focus on key fields like exit_ip, country_name, and domains:

direct_ip=$(jq -r '.exit_ip' direct_response.json)
proxy_ip=$(jq -r '.exit_ip' proxy_response.json)

direct_country=$(jq -r '.country_name' direct_response.json)
proxy_country=$(jq -r '.country_name' proxy_response.json)

echo "Direct IP: $direct_ip ($direct_country)"
echo "Proxy IP: $proxy_ip ($proxy_country)"

if [ "$direct_ip" != "$proxy_ip" ]; then
  echo "Proxy detected: IPs are different."
else
  echo "No proxy detected: IPs are the same."
fi

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Conclusion

By comparing direct and proxy responses, you can effectively detect proxy usage. Key differences in fields like exit_ip, country_name, or domains provide insights into potential anonymization. This method ensures robust proxy detection using ExtractIP geolocation API.