想将mysql 的TCP 封死，所有外部链接由我的proxy来控制，so 写了一个 tcp 转 unix socket 的 proxy。

package main

import (
	"os"
	"fmt"
	"net"
	"io"
	"sync"
	"time"
)

type proxy struct{
	Host string
	Port string
	Local string
}

func runProxy(list []proxy) {
	wg := sync.WaitGroup{}
	for _, v := range list {
		wg.Add(1)
		go func() {
			eachServer(v.Host, v.Port, v.Local)
			wg.Done()
		}()
	}
	wg.Wait()
}

func eachServer(host string, port string, local string) {
	l,err := net.Listen("tcp", fmt.Sprintf("%s:%s", host, port))
	if err != nil {
		fmt.Print("listen tcp :%s",err.Error())
		os.Exit(1)
	}
	defer l.Close()

	for {
		tc,err := l.Accept()
		if err != nil {
			fmt.Printf("accept tcp conn :%s",err.Error())
			tc.Close()
			continue
		}

		go eachConn(local, tc)
	}
}

func eachConn(local string, tc net.Conn) {
	uc,err := net.Dial("unix", local)
	if err != nil {
		fmt.Printf("get unix conn :%s",err.Error())
		uc.Close()
		return
	}
	go io.Copy(tc, uc)
	go io.Copy(uc, tc)
}

func main() {
	list := []proxy{proxy{Host:"192.168.8.101",Port:"3306",Local:"/home/work/data/tmp/mysql3306.sock"}}
	runProxy(list)
}