SPF2IP-Go

A Go implementation designed to resolve a domain's SPF (Sender Policy Framework) records into a list of IP addresses and CIDR blocks. This project is a remake of and inspired by the original Python-based SPF2IP by Nathan Dines.

This tool recursively processes SPF records, handling include and redirect mechanisms, and extracts all authorized IP networks.

Features

• Resolves SPF records for a given domain.
• Supports both IPv4 and IPv6 resolution (ip4, ip6, a, mx mechanisms).
• Handles include and redirect mechanisms recursively.
• Implements strict redirect logic (a redirect overrides preceding mechanisms in the same record).
• Detects and prevents resolution loops and excessive lookups (via include depth limit).
• Outputs all IPs and networks in canonical CIDR notation (e.g., 1.2.3.4/32, 10.0.0.0/24), sorted and unique.

Acknowledgements

This project is a Go remake of the original SPF2IP (Python) by Nathan Dines. Full credit and thanks to Nathan Dines for the original concept and implementation.

Installation

Building from Source

To build the spf2ip-go executable from source, follow these steps:

1. Clone the repository:

   git clone https://github.com/HENNGE/spf2ip-go.git
   cd spf2ip-go

2. Build the executable:

   go build github.com/HENNGE/spf2ip-go/cmd/spf2ip-go

   This will create an executable named spf2ip-go in the current directory.

Using Go Modules

If you prefer to use Go modules, you can run the following command to install the package:

go install github.com/HENNGE/spf2ip-go/cmd/spf2ip-go@latest

CLI Usage

spf2ip-go --domain <domain_name> [--ip-version <4|6>] [--debug]

Flags

• --domain <string>: (Required) The domain for which the SPF records should be resolved.
• --ip-version <int>: (Optional) The IP version to extract. Accepts 4 for IPv4 or 6 for IPv6. Defaults to 4.
• --debug: (Optional) Enable debug logging output to stderr. Defaults to false.

Examples

1. Get IPv4 addresses for example.com:

   spf2ip-go --domain example.com

2. Get IPv6 addresses for example.com:

   spf2ip-go --domain example.com --ip-version 6

3. Get IPv4 addresses for example.com with debug output:

   spf2ip-go --domain example.com --debug