main.go

package main

import (
	"flag"
	"io"
	"net"
)

func proxy(from string, to string) error {
	listener, err := net.Listen("tcp", from)
	if err != nil {
		return err
	}
	for {
		fromConn, err := listener.Accept()
		if err != nil {
			return err
		}
		toConn, err := net.Dial("tcp", to)
		if err != nil {
			return err
		}
		go io.Copy(toConn, fromConn)
		go io.Copy(fromConn, toConn)
	}
}

func main() {
	from := flag.String("from", "", "address from which we will accept connections")
	to := flag.String("to", "", "address to which we will forward traffic")
	flag.Parse()
	proxy(*from, *to)
}