asn-db is a Rust library that can load and index ASN database (ip2asn-v4.tsv file) from IPtoASN website.

Once loaded it can be used to lookup an IP address for matching ASN record that contains:

• network base IP address and mask (e.g. ipnet::Ipv4Net value like 1.1.1.0/24),
• assigned AS number (e.g. 13335),
• owner country code (e.g. US),
• owner information (e.g. CLOUDFLARENET - Cloudflare, Inc.).

It is also possible to write and then read optimized binary representation of the database to a file for fast load times. Note that at this time only IPv4 records are supported.

#Example

Load database from ip2asn-v4.tsv file and lookup 1.1.1.1 IP address.

use asn_db::Db;
use std::fs::File;
use std::io::BufReader;

let db = Db::form_tsv(BufReader::new(File::open("ip2asn-v4.tsv").unwrap())).unwrap();
let record = db.lookup("1.1.1.1".parse().unwrap()).unwrap();

println!("{:#?}", record);
println!("{:#?}", record.network());

This prints:

Record {
    ip: 16843008,
    prefix_len: 24,
    as_number: 13335,
    country: "US",
    owner: "CLOUDFLARENET - Cloudflare, Inc."
}
1.1.1.0/24