https://blog.wongcw.com/2018/10/21/telnet%e5%91%bd%e4%bb%a4%e6%b5%8b%e8%af%95%e6%9c%8d%e5%8a%a1%e5%99%a8%e7%ab%af%e5%8f%a3%e6%98%af%e5%90%a6%e9%80%9a%e7%9a%84%e5%8a%9e%e6%b3%95/