freebind-proxy

Go IP_FREEBIND HTTP Proxy

A Go implementation of an HTTP Proxy that leverages the IP_FREEBIND socket option to randomize the source IP address for outgoing HTTP requests. This proxy is compatible with both IPv6 and IPv4 subnets.

Features

• Randomized Source IPs: Makes HTTP requests with randomized IPs from a specified subnet
• IPv6 & IPv4 Support: Works seamlessly across IPv6 and IPv4 environments
• Flexible Usage: Can be used as either a standalone binary or embedded as a library

Requirements

• Linux (due to the reliance on IP_FREEBIND)
• Correctly assigned and configured network subnet on the machine

Setup

Assume your ISP has assigned the subnet 2a00:1450:4001:81b::/64 to your server.

In order to make use of freebinding, you first need to configure the Linux AnyIP kernel feature in order to be able to bind a socket to an arbitrary IP address from this subnet as follows:

ip -6 route add local 2a00:1450:4001:81b::/64 dev lo

Installation

• As a Standalone Binary:

  go install github.com/codercms/freebind-proxy/cmd/freebind-proxy@latest
  

• As an Embeddable Library:

  go get github.com/codercms/freebind-proxy
  

Usage

• Run as a Binary: After installation, execute the binary from your $GOPATH/bin:

  freebind-proxy -net 2a00:1450:4001:81b::/64
  

  See -help for more options

• Embed as a Library: Import and use in your Go project:

  import "github.com/codercms/freebind-proxy/proxy"
  

Refs

• https://github.com/blechschmidt/freebind
• https://oswalt.dev/2022/02/non-local-address-binds-in-linux/
• https://blog.widodh.nl/2016/04/anyip-bind-a-whole-subnet-to-your-linux-machine/