一、問題描述
通過sqlplus / as sysdba 無法登陸數據庫，提示權限不足。
二、模擬測試
1.現象
sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Tue Nov 14 11:09:10 2017
Copyright (c) 1982, 2013, Oracle. All rights reserved.
ERROR:
ORA-01031: insufficient privileges
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
SP2-0157: unable to CONNECT to ORACLE after 3 attempts, exiting SQL*Plus
2.使用用戶密碼登陸
<orcldg:orcl:/home/oracle>$sqlplus "sys/oracle@orcl as sysdba"
SQL*Plus: Release 11.2.0.4.0 Production on Tue Nov 14 11:09:34 2017
Copyright (c) 1982, 2013, Oracle. All rights reserved.
ERROR:
ORA-12541: TNS:no listener
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
SP2-0157: unable to CONNECT to ORACLE after 3 attempts, exiting SQL*Plus
3.啓動監聽後登陸成功
<orcldg:orcl:/home/oracle>$lsnrctl start
LSNRCTL for Linux: Version 11.2.0.4.0 - Production on 14-NOV-2017 11:09:45
Copyright (c) 1991, 2013, Oracle. All rights reserved.
Starting /u01/app/oracle/product/11.2.0/dbhome_1/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 11.2.0.4.0 - Production
System parameter file is /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
Log messages written to /u01/app/oracle/diag/tnslsnr/orcldg/listener/alert/log.xml
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=orcldg)(PORT=1521)))
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=orcldg)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version 11.2.0.4.0 - Production
Start Date 14-NOV-2017 11:09:45
Uptime 0 days 0 hr. 0 min. 0 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
Listener Log File /u01/app/oracle/diag/tnslsnr/orcldg/listener/alert/log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=orcldg)(PORT=1521)))
Services Summary...
Service "orcl" has 1 instance(s).
Instance "orcl", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully
<orcldg:orcl:/home/oracle>$sqlplus "sys/oracle@orcl as sysdba"
SQL*Plus: Release 11.2.0.4.0 Production on Tue Nov 14 11:09:52 2017
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to an idle instance.
SQL> exit
Disconnected
4.繼續提示權限不足報錯
<orcldg:orcl:/home/oracle>$sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Tue Nov 14 11:09:58 2017
Copyright (c) 1982, 2013, Oracle. All rights reserved.
ERROR:
ORA-01031: insufficient privileges
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
SP2-0157: unable to CONNECT to ORACLE after 3 attempts, exiting SQL*Plus
5.查看用戶組
<orcldg:orcl:/home/oracle>$id oracle
uid=500(oracle) gid=500(oinstall) groups=500(oinstall) --缺少dba組
<orcldg:orcl:/home/oracle>$exit
logout
6.加入dba組後登陸成功
[root@orcldg ~]# usermod -a -G oinstall,dba oracle
[root@orcldg ~]# id oracle
uid=500(oracle) gid=500(oinstall) groups=500(oinstall),501(dba)
[root@orcldg ~]# su - oracle
<orcldg:orcl:/home/oracle>$sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Tue Nov 14 11:11:07 2017
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to an idle instance.
三、小結
通常大家建庫很少關注爲什麼Oracle用戶要屬於組dba,很少關注細節。
往往我們遇到的問題，都是沒有按照規範去創建數據庫導致的，所以說建庫其實也是一個技術活。
以上問題還有可能是其他情況引起，這裏不多說。