又仔细看了下，发现好像就是连不上tidb，telnet 虽然是通的但返回不正常，
这是出问题时telnet的返回：
telnet 192.168.2.1 3390
Trying 192.168.2.1…
Connected to 192.168.2.1.
Escape character is ‘^]’.
^]
telnet> Connection closed.
这是正常时telnet 的返回：
telnet 192.168.2.1 3390
Trying 192.168.2.1…
Connected to 192.168.2.1.
Escape character is ‘^]’.
V
5.7.25-TiDB-v6.1.1˧J;n Fs¦.9bmN44]ymysql_native_password^CConnection closed by foreign host.