最近在为Oracle单实例配置ASM时，做了一些调整，结果导致sys用户无法以操作系统身份验证登陆，即提示ORA-01017错误。本文描述了这个故障的解决过程，供大家参考。

有关Oracle身份认证机制，可以参考：Oracle 密码文件

一、故障现象

[oracle@centos7 ~]$ sqlplus / as sysdba

sql*Plus: Release 11.2.0.4.0 Production on Fri Sep 22 09:52:26 2017

Copyright (c) 1982,2013,Oracle.  All rights reserved.

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

二、故障分析

1、使用oerr命令行获取详细帮助
[oracle@centos7 ~]$ oerr ora 1017
01017,00000,"invalid username/password; logon denied"
// *Cause:
// *Action:

2、查看sqlnet.ora的配置，这个文件主要定义了是否允许开启OS用户免密码登陆认证。
[oracle@centos7 ~]$ more $ORACLE_HOME/network/admin/sqlnet.ora
# sqlnet.ora Network Configuration File: /u01/oracle/db_1/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.

#NAMES.DIRECTORY_PATH= (TNSNAMES)
sqlNET.AUTHENTICATION_SERVICES = (ALL)    ###此处为ALL，表面可以使用OS认证身份验证

ADR_BASE = /u01/oracle

3、查看config.c配置文件
[oracle@centos7 ~]$ cat $ORACLE_HOME/rdbms/lib/config.c

/* SS_DBA_GRP defines the UNIX group ID for sqldba adminstrative access. */
/* Refer to the Installation and User's Guide for further information. */

/* IMPORTANT: this file needs to be in sync with rdbms/src/server/osds/config.c,specifically regarding the number of elements in the ss_dba_grp array. */

#define SS_DBA_GRP "dba" ###此处操作系统用户组定义为dba组
#define SS_OPER_GRP "oper" ###Author : Leshami
#define SS_ASM_GRP "" ###Blog : http://blog.csdn.net/leshami

char *ss_dba_grp[] = {SS_DBA_GRP,SS_OPER_GRP,SS_ASM_GRP};  

4、查看当前oracle用户所在的用户组
[oracle@centos7 ~]$ id oracle
uid=1001(oracle) gid=54321(oinstall) groups=54321(oinstall),54327(asmdba),54329(asmadmin)
从上面的结果中可知，oracle用户并不属于dba组

5、查看操作系统层面是否存在dba用户组
[oracle@centos7 ~]$ grep dba /etc/group
dba:x:54322:

通过上面的分析，应该是oracle用户所在的组不包含dba组导致无法通过操作系统层面实现身份认证。

三、故障解决

[oracle@centos7 ~]$ su - root
Password:

增加oracle用户到dba组
[root@centos7 ~]# usermod -G dba,asmdba,asmadmin oracle
[root@centos7 ~]# id oracle
uid=1001(oracle) gid=54321(oinstall) groups=54321(oinstall),54322(dba),54329(asmadmin)

[root@centos7 ~]# su - oracle
Last login: Fri Sep 22 10:03:54 CST 2017 on pts/1

再次登陆成功
[oracle@centos7 ~]$ sqlplus / as sysdba

sql*Plus: Release 11.2.0.4.0 Production on Fri Sep 22 10:27:34 2017

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

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning,OLAP,Data Mining and Real Application Testing options

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