How to Block Traffic from High-Risk Countries: A Technical Guide

Blocking traffic from high-risk countries is a common requirement for SaaS platforms, fintech applications, content services, and internal APIs. The goal is usually not to block entire regions blindly, but to reduce exposure to fraud, abuse, automated scraping, or compliance risks by making informed decisions at the network or application layer.

This article explains how country-based blocking works, how to implement it using an IP intelligence API, and what limitations backend engineers should be aware of.

What Does “High-Risk Country” Mean?

A “high-risk country” is not a fixed or universal list. It depends on your business model, threat profile, and regulatory environment.

Common reasons teams classify countries as high risk include:

• High volume of fraud attempts or payment abuse
• Automated bot traffic or credential stuffing
• Sanctions or export control restrictions
• Inability to legally serve users in certain regions
• Repeated scraping or API abuse from specific geographies

From a technical perspective, blocking traffic from high-risk countries usually means:

• Detecting the client’s country using their IP address
• Comparing it against an allowlist or blocklist
• Enforcing a policy (block, challenge, rate-limit, or log)

How IP-Based Country Detection Works?

At a high level, IP geolocation maps an IP address to metadata such as:

• Country
• Region / state
• City
• ASN (Autonomous System Number)
• ISP or organization
• IP type (residential, mobile, hosting, proxy)
• No GPS or device tracking is involved.

Using an IP Geolocation API to Detect Country

Below is an example request using an IP intelligence API.

curl https://api.ip2geoapi.com/ip/IP_ADDRESS?key=YOUR_API_KEY

You can obtain a free API key from our website. A free tier is typically sufficient for development and small-scale enforcement.

Key fields relevant for country blocking:

geo.countryCode
geo.country
version
network.asn (useful for hosting provider detection)

Implementing Country-Based Blocking

A simple approach in backend code:

• Extract the client IP from the request
• Query the IP intelligence API
• Check the country code
• Enforce a rule

Example Pseudocode:

if countryCode in BLOCKED_COUNTRIES:
    return 403 Forbidden
else:
    allow request

This logic can be implemented in:

• API gateways
• Reverse proxies
• Middleware layers
• Edge workers
• Application controllers

Real-World Use Cases

1. Fraud Prevention

Payment abuse often clusters around specific regions depending on the business. Blocking or challenging traffic from those regions reduces fraud volume before it reaches payment processors.

2. API Abuse and Scraping

If logs show sustained scraping or credential attacks originating from certain countries or hosting ASNs, geo-based filtering can reduce load and noise.

3. Compliance and Legal Restrictions

Some services cannot legally serve users from certain countries. Country detection provides an enforceable technical control.

4. Tiered Rate Limiting

Instead of hard blocking, teams often apply stricter rate limits to high-risk regions while allowing legitimate traffic through.

IPv4 vs IPv6 Considerations

Modern networks increasingly use IPv6, especially on mobile carriers.

Important points:

• Always support both IPv4 and IPv6 lookups
• Do not assume IPv4-only logic in your middleware
• Store IP addresses in normalized formats
• Ensure your IP extraction logic handles IPv6 headers correctly

The API response explicitly indicates the IP version:

"version": "ipv6"

Your enforcement logic should not treat IPv6 traffic as an exception.

Common Mistakes and Pitfalls

Blocking Entire Countries Without Context

Country-level blocking is coarse. It should be combined with:

• ASN checks
• IP reputation signals
• Rate limiting
• Behavioral analysis

Incorrect Client IP Detection

Relying blindly on X-Forwarded-For without validation can be abused. Always:

• Trust headers only from known proxies
• Validate IP formats
• Fall back to REMOTE_ADDR when needed

Ignoring Hosting and Cloud Providers

Many attacks originate from cloud providers located in “low-risk” countries. Country alone is not sufficient.

Treating Geolocation as 100% Accurate

IP geolocation is probabilistic, not absolute.

Accuracy and Edge Cases

Accuracy Limitations

• Country-level accuracy is generally high, but not perfect
• Mobile carriers may route traffic through centralized gateways
• Corporate VPNs and proxies can mask true user location

VPNs and Proxies

Users behind VPNs may appear in a different country than their actual location. Blocking by country may also block legitimate users.

Shared IP Addresses

Large ISPs and mobile networks use NAT, meaning many users share a single IP.

Because of these factors, geo-based blocking should be one signal among many.

Performance and Security Considerations

Latency

• Avoid synchronous API calls on every request for high-throughput services
• Cache IP lookup results (e.g., TTL-based caching)
• Consider edge-level enforcement for global services

Fail-Safe Behavior

Decide what happens if the IP API is unavailable:

• Allow traffic by default
• Apply conservative rate limits
• Fall back to cached data

Logging and Auditing

Log blocked requests with:

• IP address
• Country code
• Reason for block
• Timestamp

This helps refine policies and diagnose false positives.

Conclusion

Blocking traffic from high-risk countries is a practical and widely used security control, but it should be implemented carefully.

Key takeaways:

• Use IP geolocation to identify country-level risk
• Combine country checks with other signals
• Handle IPv4 and IPv6 correctly
• Expect inaccuracies and design for edge cases
• Optimize for performance with caching and fail-safe logic

When used as part of a layered security strategy, country-based blocking can significantly reduce abuse while minimizing impact on legitimate users.