----- tnsnames.ora  文件如下：
[oracle@o1930c admin]$ cat tnsnames.ora 
prod =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.52)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = prod)
    )
  )


-----使用网络远程登录 
sqlplus sys@prod as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Wed Feb 28 10:36:11 2024
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Enter password: 
ERROR:
ORA-01017: invalid username/password; logon denied



----重建密码文件orapwprod
cd $ORACLE_HOME/dbs
mv orapwprod orapwprod.bak 
orapwd file='orapwprod'  password=PROD_123_prod

sqlplus  sys@prod as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Wed Feb 28 11:11:42 2024
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Enter password: 

Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.3.0.0.0

SYS@prod> 
SYS@prod> 
SYS@prod> 
SYS@prod> 
SYS@prod> 
SYS@prod> show pdbs;

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 PDB1                           MOUNTED
SYS@prod> 


----登录成功