通过用户空间套接字的代理未按预期运行

Question

为了深入了解 Kubernetes 网络模型，我开始关注此文档。我试图SERVICE_IP通过编写此代码（来自上面共享的博客）来拦截来自用户空间的数据包。

func main() {
    clusterIP := "10.7.111.132"
    podIP := "10.5.41.204"
    port := 80
    proto := "tcp"

    addRedirectRules(clusterIP, port, proto)
    createProxy(podIP, port, proto)
}

func addRedirectRules(clusterIP string, port int, proto string) error {
    p := strconv.Itoa(port)
    cmd := exec.Command("iptables", "-t", "nat", "-A", "OUTPUT", "-p", "tcp",
        "-d", clusterIP, "--dport", p, "-j", "REDIRECT", "--to-port", p)
    return cmd.Run()
}

func createProxy(podIP string, port int, proto string) {
    host := ""
    listener, err := net.Listen(proto, net.JoinHostPort(host, strconv.Itoa(port)))

    for {
        inConn, err := listener.Accept()
        outConn, err := net.Dial(proto, net.JoinHostPort(podIP, strconv.Itoa(port)))

        go func(in, out *net.TCPConn) {
            var wg sync.WaitGroup
            wg.Add(2)
            fmt.Printf("Proxying %v <-> %v <-> %v <-> %v\n",
                in.RemoteAddr(), in.LocalAddr(), out.LocalAddr(), out.RemoteAddr())
            go copyBytes(in, out, &wg)
            go copyBytes(out, in, &wg)
            wg.Wait()
        }(inConn.(*net.TCPConn), outConn.(*net.TCPConn))
    }

    listener.Close()
}

func copyBytes(dst, src *net.TCPConn, wg *sync.WaitGroup) {
    defer wg.Done()
    if _, err := io.Copy(dst, src); err != nil {
        if !strings.HasSuffix(err.Error(), "use of closed network connection") {
            fmt.Printf("io.Copy error: %v", err)
        }
    }
    dst.Close()
    src.Close()
}

运行此命令后，我看到输出链配置如下：

Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination
1    KUBE-SERVICES  all  --  0.0.0.0/0            0.0.0.0/0            /* kubernetes service portals */
2    DOCKER     all  --  0.0.0.0/0           !127.0.0.0/8          ADDRTYPE match dst-type LOCAL
3    REDIRECT   tcp  --  0.0.0.0/0            100.65.248.49        tcp dpt:80 redir ports 80

但是我没有看到我创建的 tcp 服务器拦截了流量。作为一个网络菜鸟，我不太能解释它。任何帮助，将不胜感激