case addr.IP.To4() != nil:
				dss.teardownNetwork("tcp4")
			case addr.IP.To16() != nil && addr.IP.To4() == nil:
				dss.teardownNetwork("tcp6")
			}
			c.Close()
		}
	}
}

func TestDialerKeepAlive(t *testing.T) {
	t.Cleanup(func() {
		testHookSetKeepAlive = func(KeepAliveConfig) {}
	})

	handler := func(ls *localServer, ln Listener) {
		for {
			c, err := ln.Accept()
			if err != nil {