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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.

```rust 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:

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