A Rust utility that fetches Autonomous System Number (ASN) data including display names and IP ranges from the ipverse/asn-ip repository and outputs the results to a JSON file.

• Fetches ASN data asynchronously for improved performance
• Supports both IPv4 and IPv6 subnets
• Automatically splits large ASNs (>2000 IP ranges) into multiple entries
• Configurable ASN list via YAML file
• Outputs clean, pretty-printed JSON

[dependencies]
reqwest = { version = "0.11", features = ["json"] }
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"
serde_yaml = "0.9"
tokio = { version = "1.0", features = ["full"] }

Create a YAML file with your ASN list:

asn:
  - "13335"  # Cloudflare
  - "15169"  # Google
  - "16509"  # Amazon
  - "32934"  # Facebook

# Uses default_asn_list.yml
cargo run

# Use a custom YAML file
GET_ASN_LIST=my_asn_list.yml cargo run

• GET_ASN_LIST: Path to the YAML file containing the ASN list (default: default_asn_list.yml)

The program generates asn_data.json with the following structure:

{
  "13335": {
    "display_name": "CLOUDFLARENET",
    "ip_ranges": [
      "1.1.1.0/24",
      "1.0.0.0/24",
      "2606:4700::/32"
    ]
  }
}

ASNs with more than 2000 IP ranges are automatically split into multiple entries:

{
  "16509": {
    "display_name": "AMAZON-02",
    "ip_ranges": ["...first 2000 ranges..."]
  },
  "16509_2": {
    "display_name": "AMAZON-02_2",
    "ip_ranges": ["...next 2000 ranges..."]
  }
}

This tool fetches data from the ipverse/asn-ip repository, which provides regularly updated ASN to IP range mappings in JSON format.

• If an ASN is not found, it will be logged with "ASN {number} not found" and empty IP ranges
• Only ASNs with valid IP ranges are included in the output
• Network errors will cause the program to panic -- TODO: fix that!

# default_asn_list.yml
asn:
  - "13335"  # Cloudflare
  - "15169"  # Google LLC
  - "16509"  # Amazon.com, Inc.
  - "32934"  # Facebook, Inc.
  - "8075"   # Microsoft Corporation
  - "2906"   # Netflix, Inc.

# Build the project
cargo build --release

# Run with default configuration
cargo run

# Run with custom ASN list
GET_ASN_LIST=custom_list.yml cargo run