Prefix Fetcher

Prefix Fetcher is a Python-based tool for fetching country-specific IP prefixes from BGP data. Dynamically fetches ASN lists from Regional Internet Registry (RIR) delegated files and filters BGP prefixes accordingly.

Features

• Dynamic ASN Fetching: Automatically downloads the latest ASN allocations from RIR delegated files
  • Iran (IR): Uses RIPE NCC delegated data
  • China (CN): Uses APNIC delegated data
  • Russia (RU): Uses RIPE NCC delegated data
• Comprehensive Coverage: Fetches from all RIRs for complete ASN discovery
• BGP Data: Fetches IP prefixes from bgp.tools
• Multiple Output Formats:
  • Regular form: Original BGP prefixes as-is
  • Collapsed form: Shortest aggregated prefixes (automatically generated)
  • Split form: IPv4 as /24 blocks, IPv6 as /48 blocks (optional with --split flag)
• Clean & Simple: No caching, fresh data on every run
• Automatic retry logic with exponential backoff
• Duplicate removal: Automatically deduplicates ASNs found across multiple RIRs

Prerequisites

• Python (>=3.14)
• uv (recommended) or pip for package management

Installation

1. Clone the repository:

   git clone https://github.com/compassvpn/prefix-fetcher.git
   cd prefix-fetcher

2. Install dependencies:

   Using uv (recommended):

   uv sync

   Using pip:

   pip install -e .

Usage

Using uv:

uv run python main.py [OPTIONS]

Or after installation:

python main.py [OPTIONS]

Available Options

Option	Description
--fetch-ir	Fetch Iranian IP prefixes
--fetch-cn	Fetch Chinese IP prefixes
--fetch-ru	Fetch Russian IP prefixes
--split	Also generate split form files (IPv4 as /24, IPv6 as /48)
-h, --help	Show help information

Examples

• Fetch Iranian IP prefixes (regular and collapsed forms):

  uv run python main.py --fetch-ir

• Fetch Chinese IP prefixes with split form:

  uv run python main.py --fetch-cn --split

• Fetch Russian IP prefixes:

  uv run python main.py --fetch-ru

• Fetch multiple countries with split form:

  uv run python main.py --fetch-ir --fetch-cn --fetch-ru --split

• Show help:

  uv run python main.py --help

Output Files

The tool generates country-specific prefix files in multiple formats:

Always Generated

Regular form (original BGP prefixes):

• ir_prefixes_v4.txt / ir_prefixes_v6.txt
• cn_prefixes_v4.txt / cn_prefixes_v6.txt
• ru_prefixes_v4.txt / ru_prefixes_v6.txt

Collapsed form (shortest aggregated prefixes):

• ir_prefixes_v4_collapsed.txt / ir_prefixes_v6_collapsed.txt
• cn_prefixes_v4_collapsed.txt / cn_prefixes_v6_collapsed.txt
• ru_prefixes_v4_collapsed.txt / ru_prefixes_v6_collapsed.txt

Optional (with --split flag)

Split form (IPv4 as /24 blocks, IPv6 as /48 blocks):

• ir_prefixes_v4_split.txt / ir_prefixes_v6_split.txt
• cn_prefixes_v4_split.txt / cn_prefixes_v6_split.txt
• ru_prefixes_v4_split.txt / ru_prefixes_v6_split.txt

Format Descriptions

• Regular: Original BGP prefixes as announced (varying prefix lengths)
• Collapsed: Optimized/aggregated prefixes merged into shortest possible form
• Split: Normalized to fixed-size blocks (/24 for IPv4, /48 for IPv6)

How It Works

1. Fetches ASN Lists: Downloads the latest ASN allocations from all RIRs for comprehensive coverage:
   • Iran: Primary coverage from RIPE NCC, with additional checks across all RIRs
   • China: Primary coverage from APNIC, with additional checks across all RIRs
   • Russia: Primary coverage from RIPE NCC, with additional checks across all RIRs
2. Downloads BGP Data: Fetches the complete BGP routing table from bgp.tools
3. Filters by ASN: Keeps only prefixes from the dynamically fetched ASN lists
4. Generates Multiple Formats:
   • Regular: Saves original BGP prefixes
   • Collapsed: Aggregates overlapping/adjacent prefixes into shortest form using Python's collapse_addresses()
   • Split (optional): Normalizes IPv4 to /24 blocks and IPv6 to /48 blocks using subnets() method
5. Sorts and Saves: Outputs clean, sorted prefix lists to text files

Data Sources

• RIR Delegated Files:
  • Iran: RIPE NCC (+ all other RIRs)
  • China: APNIC (+ all other RIRs)
  • Russia: RIPE NCC (+ all other RIRs)
• BGP Data: bgp.tools

License

This project is licensed under the MIT License.

Contributions

Contributions are welcome! Feel free to fork the repository and submit a pull request.