mysql client v5.7.26 connect to tidb master fail for unknown error number

[seiya-annie]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

root@wkload-0:/tools# /root/opt/mysql/5.1.72/bin/mysql -u nopw -h tc-tidb.testbed-endless-client-ncjv5 -P 4000 -e QUIT
root@wkload-0:/tools# /root/opt/mysql/5.7.26/bin/mysql -u nopw -h tc-tidb.testbed-endless-client-ncjv5 -P 4000 -e QUIT
ERROR 2026 (HY000): SSL connection error: unknown error number
root@wkload-0:/tools# /root/opt/mysql/8.0.17/bin/mysql -u nopw -h tc-tidb.testbed-endless-client-ncjv5 -P 4000 -e QUIT
root@wkload-0:/tools#

2. What did you expect to see? (Required)

mysql client v5.7.26 can connect to master

3. What did you see instead (Required)

root@wkload-0:/tools# /root/opt/mysql/5.7.26/bin/mysql -u nopw -h tc-tidb.testbed-endless-client-ncjv5 -P 4000 -e QUIT
ERROR 2026 (HY000): SSL connection error: unknown error number

4. What is your TiDB version? (Required)

master

[hawkingrei]

It is designed by #36037.

MySQL 5.7 uses tls1.x as the default tls version. but it is deprecated in the mysql8.0.

You can read this in detail.