如何使用Golang实现简单的端口转发服务

package main

import (
    "io"
    "log"
    "net"
)

func main() {
    listener, err := net.Listen("tcp", "127.0.0.1:9000")
    if err != nil {
        log.Fatal("listen error:", err)
    }
    defer listener.Close()
    for {
        conn, err := listener.Accept()
        if err != nil {
            log.Fatal("accept error:", err)
        }
        go forward(conn)
    }
}

func forward(localConn net.Conn) {
    remoteConn, err := net.Dial("tcp", "remote_server_ip:remote_server_port")
    if err != nil {
        localConn.Close()
        return
    }
    defer remoteConn.Close()
    go io.Copy(localConn, remoteConn)
    io.Copy(remoteConn, localConn)
}