Let‘s explore what ASNs can reveal about network security, the many options for looking them up, and how to choose the right tool for your cyber analytics needs.
What Are Autonomous System Numbers and Why Do They Matter?
Autonomous system numbers or ASNs serve as critical identifiers in the global routing system that powers the decentralized internet. Here‘s a quick 4-1-1 on what they are and what security insights ASNs can provide:
Definition: An ASN refers to a unique number assigned to a group of networked computer resources that operate under a single administrative policy. These autonomous systems exchange routing information to transport traffic across network boundaries.
Public ASNs facilitate data transfers on the global public internet infrastructure. Meanwhile private ASNs communicate routing data with only one internet provider.
Now that sums up the technical explanation of ASNs. But from an information security perspective, here are some key reasons they‘re so important:
- Reveal ownership and geographic location for an IP address or network
- Provide visibility into traffic routing paths across the internet
- Help identify suspicious interconnectivity and potential threats
- Enrich threat intel data with more comprehensive context
Having reliable lookup tools for mapping, analyzing and correlating ASN data enables much more robust network monitoring, investigation workflows, and security analytics.
So whether you‘re an IT pro, cyber defender or internet infrastructure specialist, understanding ASNs should be fundamental to your network visibility toolkit!
Types of ASN Lookup Methods and Tools
If you want to harness ASNs for security analysis, verification or network management, what options exist? Here is an at-a-glance view of common ASN lookup approaches:
| Lookup Method | Description |
|---|---|
| Online Databases | Web-based interfaces for querying ASNs or IPs to retrieve related data |
| Command Line Tools | Enable ASN investigation directly from terminal using utilities like whois, dig |
| APIs | Provide programmatic access to ASN records for integration with scripts, apps |
| Bulk Lookups | Allow high volume ASN/IP queries in batches via files for expanded analysis |
In 2023, the ASN lookup ecosystem offers great diversity across these fronts. After covering some key factors for comparison, we‘ll highlight top options in each category.
Our focus will be tools suitable for ad hoc lookups or lightweight automation. But we‘ll also showcase more advanced alternatives for large-scale querying or public data enrichment.
Let‘s examine what to consider when evaluating ASN investigation utilities:
Key Evaluation Criteria
- Inputs: What identifiers can be searched – ASN, IP, name, domain, etc?
- Outputs: What data is returned – ownership, IPs, locations, relationships?
- Presentation: Is it an API, web app, command line tool?
- Ease-of-Use: How intuitive and accessible is the interface?
- Pricing: What usage limits or costs apply?
Balancing those factors based on your use case is vital for getting maximum value. Now let‘s explore top ASN investigation tools in various categories.
#1 UltraDNS for Reliable Web Lookups
Overview: UltraDNS offers one of the cleanest and user-friendly web interfaces for querying details on a specific ASN or IP address. Its presentation of registration, allocation and routing data makes it easy to inspect relationships.
Key Capabilities:
- Supports lookups by ASN, IP address or domain
- Displays full ownership, geographic and registration details
- Shows associated network ranges under ASN prefix
- Prevalent operator details along with network interconnectivity
- No signup required and completely free to use
Say we want to validate ownership info for the ASN tied to major cloud infrastructure provider, DigitalOcean. Entering their public AS14061 instantly retrieves the following:
[Insert screenshot of UltraDNS sample output]The clean specificity delivered in seconds makes manual inspection effortless. For one-off verification or exploratory analysis, UltraDNS shines.
Downsides: Lacks bulk querying capabilities or API access useful for automation at scale. But for ad hoc human-driven lookups, it‘s unmatched.
#2 APNIC – Leading ASN Authority for Asia Pacific
Regional internet registries like APNIC maintain canonical ASN assignment records. For Asia Pacific, APNIC stewards this authoritative data providing primary source lookup capacity:
Standout Features:
- Look up by ASN, IP block, registry ID or owner details
- View critical dates, registration contacts and more
- Supports partial keyword searches
- Embedded web access or CLI termination
For example, passing AS9829 assigned to NETFLIX yields:
[Insert APNIC Lookup Sample]With 78,000+ ASNs in APNIC‘s registry as of 2023, having this lookup avenue enables verification using quality primary source data.
Tradeoffs: Covers only Asia Pacific resources so can‘t displace tools with global scope. But for confirmation or enriching regional threat data, it‘s invaluable.
#3 ASNLookup API for Automated Enrichment
While most lookup tools focus on manual investigation, ASNLookup specializes in enabling integration with scripts and applications via its developer-friendly JSON API.
Automation Highlights:
- Clean REST API supporting ASN or name queries
- Returns registration details, locations and netblocks
- No usage limits or keys – completely open and free
- Helper libraries for instant integration
This API call retrieving Cloudflare‘s ASN data demonstrates the formatting:
https://asnlookup.com/api/lookup?org=cloudflareFor annotating network artifacts at scale or enriching threat feeds, ASNLookup parallelizes lookup burdens.
Constraints: It lacks a web interface for ad hoc manual interaction. But for automation purposes, the API is gold.
#4 Team Cymru for Bulk ASN Conversion
While most online ASN utilities focus on single entity lookups, Team Cymru deserves mention for enabling high volume batch queries – critical for large-scale processing.
Bulk Analysis Features:
- Accepts lists of IPs for conversion to associated ASNs
- Output formats like CSV for stacking enrichment data
- Handy API for integration into pipelines
- Free membership provides ample processing
This bulk handling makes Cymru shine for enriching SIEM data, threat intel feeds and network artifact analysis.
[Insert Team Cymru Bulk Upload Screenshot]Shortcomings: The enrichment data itself is fairly minimal compared to other tools. But the batch automation bridges a major lookup gap.
#5 Hurricane Electric for Advanced BGP Interrogation
While Hurricane Electric‘s BGP toolkit caters more towards network engineers, it deserves a nod for unlocking views granted by few other offerings.
Unique BGP-derived Insights:
- Reveals upstream transit providers for ASN
- Enumerates downstream customer networks
- Maps geographic infrastructure topology
- Ideal for Internet infrastructure experts
Unlocking these intelligence avenues leveraging Border Gateway Protocol data enables monitoring of networking shifts tied to threat groups or suspicious AS patterns.
[Insert Hurricane Electric BGPlookup Sample]The learning investment is rewarded with rare transitory analysis capacity unlocked by Hurricane‘s toolkit.
#6 ipinfo.io API for Flexible Automation
Prefer ASN integration using modern REST conventions over legacy command line tooling? ipinfo delivers a robust API in a tidy package:
Developer Highlights:
- JSON API supporting ASN or IP lookup
- Helper libraries for dozens of programming languages
- Clean documentation and query structuring
- Free tier allowing 50k monthly queries
Combined with lightning fast performance like such:
https://ipinfo.io/AS15169?token=xxx
RESPONSE:
{
"asn": "AS15169",
"name": "Google LLC",
"country": "US",
"description": "Google LLC"
}The output combines autonomy with simplicity – perfect for building ASN context into apps.
Limitations: No web interface for ad hoc lookup is the tradeoff. But the API experience warrants inclusion.
Conclusion and Recommendations
Having explored various facets of ASN investigation utilities through an infosec lens, let‘s connect the final dots on recommendations:
- Ad hoc investigation: UltraDNS offers an unparalleled user experience for verification lookup supported by Hurricane Electric‘s BGP toolkit for advanced routing analysis. Leverage APNIC for authoritative regional registry queries.
- Automation and enrichment: ASNLookup, Team Cymru and ipinfo.io shine for integration with security infrastructure using APIs. Build lookup capabilities into analytics and intelligence workflows.
- Benchmarking and decisioning: Factor in key considerations around inputs, outputs, access method and usage limits covered in this guide when evaluating tools.
By mapping capabilities to use cases, while considering evaluation criteria, you‘re equipped to strategically select solutions for embedding ASN intelligence. This lifts visibility into relationships and patterns that enable proactive threat detection powered by next generation network analysis.
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