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IP ASN mapping algorithm

Is there an easy way to map this IP address to the corresponding ASN? For example:

ping to find the IP address:

$ ping www.switch.ch PING aslan.switch.ch (130.59.108.36) 56(84) bytes of data.

whois is looking for an ASN number:

 $ whois -h whois.cymru.com -v 130.59.108.36 Warning: RIPE flags used with a traditional server. AS | IP | BGP Prefix | CC | Registry | Allocated | AS Name 559 | 130.59.108.36 | 130.59.0.0/16 | CH | ripencc | 1993-09-22 | SWITCH SWITCH, Swiss Education and Research Network

Thus, the mapping in this case will be 130.59.108.36 (IP) → 559 (ASN). Easy. But what if I would like to create my own local mapping service with publicly available information from regional Internet registries? So, for the above example, this will be this list, right?

 ftp://ftp.ripe.net/pub/stats/ripencc/delegated-ripencc-latest

And finding a matching entrie is also not a problem:

 ripencc|CH|ipv4|130.59.0.0|65536|19930922|assigned

But how do I get the ASN number from the line above? How are these two information related?

 ripencc|EU|asn|559|1|19930901|allocated

Thanks in advance for your reply!

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I will explain how to do it here: https://www.quaxio.com/bgp/ (previously at https://alokmenghrajani.imtqy.com/bgp/ )

This is mainly due to loading the dump from the router, and then using the efficient presentation of the data to map the IP address to the network mask.

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I would suggest doing this based on MRT dumps compiled from real BGP dynamics.

There is this python fe library that can be used to easily analyze MRT dumps: http://code.google.com/p/pyasn/

If you cannot start your own BGP speaker, you can download dumps at http://archive.routeviews.org/

Make sure you check other things as well. They also provide DNS zones that will allow you to perform such queries using a standard DNS server such as Bind or NSD: http://archive.routeviews.org/dnszones/

I hope you get started ...

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I created a tool that adds ASN to the HTTP protocol strings. I will explain how to create a database from raw RIPE data and use it with binary search. In addition, the C code is ready to use. 1.6M in a few seconds on a regular virtual instance:

https://github.com/psvz/tirexASN

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