应用监控程序报No matching authentication protocol，无法登陆数据库
https://www.cnblogs.com/lhrbest/p/6219687.html
1：12c与11g的区别
使用oerr命令来查看，在Oracle 11g下：
[oracle@orcltest ~]$ oerr ora 28040
28040, 0000, "No matching authentication protocol"
// *Cause: No acceptible authentication protocol for both client and server
// *Action: Administrator should set SQLNET_ALLOWED_LOGON_VERSION parameter
// on both client and servers to values that matches the minimum
// version supported in the system.
[oracle@orcltest ~]$
12c下：
oracle@HQsPSL-PSCV-R02:/oracle/app/oracle> oerr ora 28040
28040, 0000, "No matching authentication protocol"
// *Cause: There was no acceptable authentication protocol for
// either client or server.
// *Action: The administrator should set the values of the
// SQLNET.ALLOWED_LOGON_VERSION_SERVER and
// SQLNET.ALLOWED_LOGON_VERSION_CLIENT parameters, on both the
// client and on the server, to values that match the minimum
// version software supported in the system.
// This error is also raised when the client is authenticating to
// a user account which was created without a verifier suitable for
// the client software version. In this situation, that account's
// password must be reset, in order for the required verifier to
可以看到，该参数在11g和12c下的解决方案是不同的。
查询了一下参数SQLNET.ALLOWED_LOGON_VERSION，发现该参数在12c中以废弃，而是采用SQLNET.ALLOWED_LOGON_VERSION_CLIENT和SQLNET.ALLOWED_LOGON_VERSION_SERVER代替。
客户说是之前碰到了ORA-28040: No matching authentication protocol的错误才加上该参数的。
解决：在Oracle用户（不是grid用户）下，将$ORACLE_HOME/network/admin/sqlnet.ora文件原来的SQLNET.ALLOWED_LOGON_VERSION=8注释掉（如果没有sqlnet.ora文件，那么就创建一个），修改为如下的行：
SQLNET.ALLOWED_LOGON_VERSION_SERVER=8
SQLNET.ALLOWED_LOGON_VERSION_CLIENT=8
2：此时可连接进行查看，且因为登陆账号被锁，密码错误，则进行修改解锁切且修改密码后可以进入
alter user testOracle2019 account unlock; -------解锁账户 alter user testOracle2019 identified by testOracle2019 ; -------------修改密码 附一个连接的驱动包：
https://download.oracle.com/otn/utilities_drivers/jdbc/121010/ojdbc7.jar
附：idea连接oracle方法
