text/rude-rejection

func Dial(addr, passwd string) (*Connection, error) {
	c, err := net.Dial("tcp", addr)
	if err != nil {
		return nil, err
	}
	h := newConnection(c)
	m, err := h.textreader.ReadMIMEHeader()
	if err != nil {
		c.Close()
		return nil, err
	}
	if m.Get("Content-Type") != "auth/request" {                       //text/rude-rejection
		c.Close()
		return nil, errMissingAuthRequest
	}