How to Detect VPNs, Data Centers, and Suspicious Traffic Using ASN Data
Most developers think about IP intelligence in terms of geolocation.
Questions like:
- Which country is this user from?
- Which city are they connecting from?
- What language should I show?
are common.
But after working with APIs, analytics, and security systems, I've found that ASN data is often more useful than country data.
If you're building authentication systems, fraud detection, analytics platforms, or API security controls, ASN information can provide context that geolocation alone cannot.
What Is an ASN?
ASN stands for Autonomous System Number.
Every major ISP, cloud provider, mobile carrier, and network operator on the internet is assigned one or more ASNs.
Examples include:
- Amazon AWS
- Microsoft Azure
- Cloudflare
- Telstra
- Comcast
Why ASN Data Matters
Imagine a user signs up from an IP address located in Australia.
Traditional GeoIP data might tell you the country and city.
But ASN data might tell you the traffic originates from Amazon AWS rather than a residential internet connection.
That additional context can be extremely valuable.
Detecting Data Center Traffic
Many bots, scrapers, and automated systems operate from cloud providers.
Common examples:
- AWS
- Azure
- Google Cloud
- DigitalOcean
- Vultr
- Oracle Cloud
If your application receives large volumes of registrations or API requests from these providers, ASN data can help identify patterns.
This doesn't automatically mean the traffic is malicious.
But it does provide another signal that can be combined with:
- Rate limits
- Device fingerprints
- User behavior
- Reputation systems
Detecting VPN Usage
Many VPN providers operate infrastructure from hosting providers and data centers.
While ASN data alone cannot definitively identify every VPN user, it can help detect traffic that originates from networks commonly associated with VPN infrastructure.
Fraud Prevention
ASN data is particularly useful during:
- User registration
- Account recovery
- Login verification
- Payment processing
ASN is not a final decision-maker.
It's another signal that helps build a risk profile.
Analytics and Reporting
ASN information can also improve visibility into your user base.
Questions you can answer include:
- How much traffic comes from mobile carriers?
- How much traffic comes from cloud providers?
- Which ISPs are most common?
- Which networks generate the most abuse reports?
Example Lookup
A simple ASN lookup can provide:
- Geographic location
- Network owner
- ASN information
Final Thoughts
Country-level geolocation is useful.
ASN intelligence often provides the context that makes that geolocation meaningful.
If you're building authentication systems, fraud detection tools, analytics platforms, or API security controls, then ASN data is worth paying attention to.
Example lookups in this article were performed using IPRout, a developer-first GeoIP and ASN API currently in public beta.
Website: https://iprout.com
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