【方法】如何限定IP访问Oracle数据库

1.1  BLOG文档结构图

1.2  前言部分

1.2.1  导读和注意事项

各位技术爱好者，看完本文后，你可以掌握如下的技能，也可以学到一些其它你所不知道的知识，~O(∩_∩)O~：

① 限定IP访问Oracle数据库的3种方法（重点）

② 如何将信息写入到Oracle的告警日志中

③ RAISE_APPLICATION_ERROR不能抛出错误到客户端环境

④ 系统触发器

⑤ 隐含参数：_system_trig_enabled

Tips：

① 本文在itpub（http://blog.itpub.net/26736162）、博客园(http://www.cnblogs.com/lhrbest)和微信公众号（xiaomaimiaolhr）上有同步更新。

② 文章中用到的所有代码、相关软件、相关资料及本文的pdf版本都请前往小麦苗的云盘下载，小麦苗的云盘地址见：http://blog.itpub.net/26736162/viewspace-1624453/。

③ 若网页文章代码格式有错乱，请下载pdf格式的文档来阅读。

④ 在本篇BLOG中，代码输出部分一般放在一行一列的表格中。

本文若有错误或不完善的地方请大家多多指正，您的批评指正是我写作的最大动力。

1.3  本文简介

本文详细介绍了3种限制IP地址登录Oracle数据库的办法。

1.3.1  本文实验环境介绍

1.4  限定IP访问Oracle数据库的3种办法

1.4.1  利用登录触发器

1.4.1.1  简单版

客户端登录：

告警日志无输出。

1.4.1.2  复杂版

复杂版就是需要记录登录日志，并把报错信息输出到告警日志中。

客户端登录：

告警日志：

查询日志表：

SELECT * FROM XB_AUDIT_LOGON_LHR;

1.4.1.3  注意事项

需要注意的问题：

① 触发的对象类型可以为DATABASE，也可以为“用户名.SCHEMA”，如：

AFTER LOGON ON DATABASE

AFTER LOGON ON SCOTT.SCHEMA

② 当触发的对象类型为DATABASE的时候，登录用户不能拥有“ADMINISTER DATABASE TRIGGER”的系统权限；当触发的对象类型为“用户名.SCHEMA”的时候，登录用户不能拥有“ALTER ANY TRIGGER”的系统权限。否则，这些用户还是会正常登录到数据库，只是将相应的报错信息写入到告警日志中。所以，拥有IMP_FULL_DATABASE和DBA角色的用户以及SYS和EXFSYS用户将不能通过这种方式限制登录。

③ 隐含参数“_SYSTEM_TRIG_ENABLED”的默认值是TRUE，即允许DDL和系统触发器。当设置隐含参数“_SYSTEM_TRIG_ENABLED”为FALSE的时候，将禁用DDL和系统触发器。所以，当该值设置为FALSE的时候将不能通过这种方式限制登录。

一、 测试第二点

第二点测试如下：

客户端登录：

告警日志：

继续测试：

客户端继续登录，发现不能正常登录。将触发器中的AFTER LOGON ON DATABASE修改为AFTER LOGON ON LHR8.SCHEMA，其他不变，继续测试：

发现可以正常登录了，告警日志：

二、 测试第三点

将触发器中的AFTER LOGON ON LHR8.SCHEMA修改为AFTER LOGON ON DATABASE，其他不变，继续测试:

不能正常登录，下面禁用系统触发器：

进行登录：

发现可以正常登录了。将参数"_system_trig_enabled"修改回原值。

1.4.1.4  利用登录触发器实现时间段登录

Use Event Triggers

------------------

If you allow the users to log in the database only from Monday to Friday included,

and from 8AM to 6PM, create an event trigger that checks after logon on

database for each user (except the DBA users) that the connection occurs only

within this timeframe.

Example 1

-------

1. No check set up yet: any ordinary user can log into the database:

    SQL> connect test_trigger/test_trigger

    Connected.

2. The DBA creates an event trigger that checks if the connection occurs

    between Monday and Friday , and within working hours: 8AM to 6PM.

    Trigger created.

3. It is Friday   5PM : an ordinary user can log into the database:

Example 2

-------

Another example to restrict the logon periods for a users so that they can only

access the database betrween the periods to 17:00 - 24:00 daily.

If the user attempts to logon during a period outside of this range his logon

attempt will fail:

However, users with ADMINISTER DATABASE TRIGGER system privilege can log into

the database any time.

1.4.2  利用sqlnet.ora

第二种是修改$ORACLE_HOME/network/admin/sqlnet.ora文件，增加如下内容：

之后重新启动监听器即可。这样客户端在登录的时候会报“ORA-12537: TNS:connection closed”的错误。

需要注意的问题：

① 需要设置参数TCP.VALIDNODE_CHECKING为YES才能激活该特性。

② 一定要许可或不要禁止数据库服务器本机的IP地址，否则通过lsnrctl将不能启动或停止监听，因为该过程监听程序会通过本机的IP访问监听器，而该IP被禁止了，但是通过服务启动或关闭则不影响。

③ 当参数TCP.INVITED_NODES和TCP.EXCLUDED_NODES设置的地址相同的时候以TCP.INVITED_NODES的配置为主。

④ 修改之后，一定要重起监听才能生效，而不需要重新启动数据库。

⑤ 这个方式只是适合TCP/IP协议。

⑥ 这个配置适用于Oracle 9i以上版本。在Oracle 9i之前的版本使用文件protocol.ora。

⑦ 在服务器上直接连接数据库不受影响。

⑧ 这种限制方式是通过监听器来限制的。

⑨ 这个限制只是针对IP检测，对于用户名检测是不支持的。

删除之前创建的触发器，继续测试。

重启监听：

客户端连接：

监听报错：

使用192.168.59.1客户端进行登录：

发现可以正常登录。将TCP.INVITED_NODES的IP里加入192.168网段，则可以正常登录:

客户端登录：

1.4.3  利用防火墙

第3种是修改数据库服务器的IPTABLES（配置文件：/etc/sysconfig/iptables）来限制某些IP登录数据库服务器。如下：

则，192.168.59.129这台主机将不能连接到数据库服务器了，会报“ORA-12170: TNS:Connect timeout occurred”的错误。

测试：

该部分可以参考网络配置，小麦苗从网上找了很多。

我们可以通过以下的iptables的设置来限制用户访问oracle所在linux操作系统的安全。

1、清楚操作系统默认的iptables策略

      我本机安装的是centos6.0,安装之后系统会提供iptables默认的policy策略,我们首先要清楚默认的策略

      iptables -F

2、开发22和1521端口对局域网的某个IP，在本例中客户端ip是192.168.1.125,oracle所在机器的IP是192.168.1.144,在这里，设置仅有该客户端可以访问22和1521端口，局域网内的其他IP都不允许访问，

    iptables -A INPUT -s 192.168.1.125/32 -i eth0 -p tcp  --dport 22 -j ACCEPT

    iptables -A INPUT -s 192.168.1.125/32 -i eth0 -p tcp  --dport 1521 -j ACCEPT

    iptables -A INPUT -s 192.168.1.0/24 -p tcp  --dport 22 -j DROP

    iptables -A INPUT -s 192.168.1.0/24 -p tcp  --dport 1521 -j DROP

    这样同一网段内除192.168.1.125之外其他IP都不能访问数据库服务器，即使ping命令也不可以

3、开发22和1521的OUTPUT链给192.168.1.125，否则已经启动的oracle instance的pmon进程无法动态注册到1521端口中

     iptables -A OUTPUT -d 192.168.1.125/32 -p tcp  --sport 22 -j ACCEPT

     iptables -A OUTPUT -d 192.168.1.125/32 -p tcp --sport 1521 -j ACCEPT

4、保存当前设置的iptables规则

      service iptables save

      这时系统会将已经设置的规则保存到/etc/sysconfig/iptables文件中

      否则重启之后之前设置的规则都会失效

先关闭所有的80端口

开启ip段192.168.1.0/24端的80口

开启ip段211.123.16.123/24端ip段的80口

# iptables -I INPUT -p tcp --dport 80 -j DROP

# iptables -I INPUT -s 192.168.1.0/24 -p tcp --dport 80 -j ACCEPT

# iptables -I INPUT -s 211.123.16.123/24 -p tcp --dport 80 -j ACCEPT

以上是临时设置。

1.先备份iptables

# cp /etc/sysconfig/iptables /var/tmp

2.然后保存iptables

# service iptables save

3.重启防火墙

#service iptables restart

以下是端口，先全部封再开某些的IP

iptables -I INPUT -p tcp --dport 9889 -j DROP

iptables -I INPUT -s 192.168.1.0/24 -p tcp --dport 9889 -j ACCEPT

如果用了NAT转发记得配合以下才能生效

iptables -I FORWARD -p tcp --dport 80 -j DROP

iptables -I FORWARD -s 192.168.1.0/24 -p tcp --dport 80 -j ACCEPT

常用的IPTABLES规则如下：

只能收发邮件，别的都关闭

iptables -I Filter -m mac --mac-source 00:0F:EA:25:51:37 -j DROP

iptables -I Filter -m mac --mac-source 00:0F:EA:25:51:37 -p udp --dport 53 -j ACCEPT

iptables -I Filter -m mac --mac-source 00:0F:EA:25:51:37 -p tcp --dport 25 -j ACCEPT

iptables -I Filter -m mac --mac-source 00:0F:EA:25:51:37 -p tcp --dport 110 -j ACCEPT

IPSEC NAT 策略

iptables -I PFWanPriv -d 192.168.100.2 -j ACCEPT

iptables -t nat -A PREROUTING -p tcp --dport 80 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.2:80

iptables -t nat -A PREROUTING -p tcp --dport 1723 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.2:1723

iptables -t nat -A PREROUTING -p udp --dport 1723 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.2:1723

iptables -t nat -A PREROUTING -p udp --dport 500 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.2:500

iptables -t nat -A PREROUTING -p udp --dport 4500 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.2:4500

FTP服务器的NAT

iptables -I PFWanPriv -p tcp --dport 21 -d 192.168.100.200 -j ACCEPT

iptables -t nat -A PREROUTING -p tcp --dport 21 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.200:21

只允许访问指定网址

iptables -A Filter -p udp --dport 53 -j ACCEPT

iptables -A Filter -p tcp --dport 53 -j ACCEPT

iptables -A Filter -d www.3322.org -j ACCEPT

iptables -A Filter -d img.cn99.com -j ACCEPT

iptables -A Filter -j DROP

开放一个IP的一些端口，其它都封闭

iptables -A Filter -p tcp --dport 80 -s 192.168.100.200 -d www.pconline.com.cn -j ACCEPT

iptables -A Filter -p tcp --dport 25 -s 192.168.100.200 -j ACCEPT

iptables -A Filter -p tcp --dport 109 -s 192.168.100.200 -j ACCEPT

iptables -A Filter -p tcp --dport 110 -s 192.168.100.200 -j ACCEPT

iptables -A Filter -p tcp --dport 53 -j ACCEPT

iptables -A Filter -p udp --dport 53 -j ACCEPT

iptables -A Filter -j DROP

多个端口

iptables -A Filter -p tcp -m multiport --destination-port 22,53,80,110 -s 192.168.20.3 -j REJECT

连续端口

iptables -A Filter -p tcp -m multiport --source-port 22,53,80,110 -s 192.168.20.3 -j REJECT iptables -A Filter -p tcp --source-port 2:80 -s 192.168.20.3 -j REJECT

指定时间上网

iptables -A Filter -s 10.10.10.253 -m time --timestart 6:00 --timestop 11:00 --days Mon,Tue,Wed,Thu,Fri,Sat,Sun -j DROP

iptables -A Filter -m time --timestart 12:00 --timestop 13:00 --days Mon,Tue,Wed,Thu,Fri,Sat,Sun -j ACCEPT

iptables -A Filter -m time --timestart 17:30 --timestop 8:30 --days Mon,Tue,Wed,Thu,Fri,Sat,Sun -j ACCEPT

禁止多个端口服务

iptables -A Filter -m multiport -p tcp --dport 21,23,80 -j ACCEPT

将WAN 口NAT到PC

iptables -t nat -A PREROUTING -i $INTERNET_IF -d $INTERNET_ADDR -j DNAT --to-destination 192.168.0.1

将WAN口8000端口NAT到192。168。100。200的80端口

iptables -t nat -A PREROUTING -p tcp --dport 8000 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.200:80

MAIL服务器要转的端口

iptables -t nat -A PREROUTING -p tcp --dport 110 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.200:110

iptables -t nat -A PREROUTING -p tcp --dport 25 -d $INTERNET_ADDR -j DNAT --to-destination 192.168.100.200:25

只允许PING 202。96。134。133,别的服务都禁止

iptables -A Filter -p icmp -s 192.168.100.200 -d 202.96.134.133 -j ACCEPT

iptables -A Filter -j DROP

禁用BT配置

iptables –A Filter –p tcp –dport 6000:20000 –j DROP

禁用QQ防火墙配置

iptables -A Filter -p udp --dport ! 53 -j DROP

iptables -A Filter -d 218.17.209.0/24 -j DROP

iptables -A Filter -d 218.18.95.0/24 -j DROP

iptables -A Filter -d 219.133.40.177 -j DROP

基于MAC，只能收发邮件，其它都拒绝

iptables -I Filter -m mac --mac-source 00:0A:EB:97:79:A1 -j DROP

iptables -I Filter -m mac --mac-source 00:0A:EB:97:79:A1 -p tcp --dport 25 -j ACCEPT

iptables -I Filter -m mac --mac-source 00:0A:EB:97:79:A1 -p tcp --dport 110 -j ACCEPT

禁用MSN配置

iptables -A Filter -p udp --dport 9 -j DROP

iptables -A Filter -p tcp --dport 1863 -j DROP

iptables -A Filter -p tcp --dport 80 -d 207.68.178.238 -j DROP

iptables -A Filter -p tcp --dport 80 -d 207.46.110.0/24 -j DROP

只允许PING 202。96。134。133 其它公网IP都不许PING

iptables -A Filter -p icmp -s 192.168.100.200 -d 202.96.134.133 -j ACCEPT

iptables -A Filter -p icmp -j DROP

禁止某个MAC地址访问internet:

iptables -I Filter -m mac --mac-source 00:20:18:8F:72:F8 -j DROP

禁止某个IP地址的PING:

iptables –A Filter –p icmp –s 192.168.0.1 –j DROP

禁止某个IP地址服务：

iptables –A Filter -p tcp -s 192.168.0.1 --dport 80 -j DROP

iptables –A Filter -p udp -s 192.168.0.1 --dport 53 -j DROP

只允许某些服务，其他都拒绝(2条规则)

iptables -A Filter -p tcp -s 192.168.0.1 --dport 1000 -j ACCEPT

iptables -A Filter -j DROP

禁止某个IP地址的某个端口服务

iptables -A Filter -p tcp -s 10.10.10.253 --dport 80 -j ACCEPT

iptables -A Filter -p tcp -s 10.10.10.253 --dport 80 -j DROP

禁止某个MAC地址的某个端口服务

iptables -I Filter -p tcp -m mac --mac-source 00:20:18:8F:72:F8 --dport 80 -j DROP

禁止某个MAC地址访问internet:

iptables -I Filter -m mac --mac-source 00:11:22:33:44:55 -j DROP

禁止某个IP地址的PING:

iptables –A Filter –p icmp –s 192.168.0.1 –j DROP

1.5  本文总结

在Oracle中，有3种办法可以限定特定IP访问数据库。第一种是利用登录触发器，如下：

需要注意的问题：

① 触发的对象类型可以为DATABASE，也可以为“用户名.SCHEMA”，如：

② 当触发的对象类型为DATABASE的时候，登录用户不能拥有“ADMINISTER DATABASE TRIGGER”的系统权限；当触发的对象类型为“用户名.SCHEMA”的时候，登录用户不能拥有“ALTER ANY TIGGER”的系统权限。否则，这些用户还是会正常登录到数据库，只是将相应的报错信息写入到告警日志中。所以，拥有IMP_FULL_DATABASE和DBA角色的用户以及SYS和EXFSYS用户将不能通过这种方式限制登录。

③ 隐含参数“_SYSTEM_TRIG_ENABLED”的默认值是TRUE，即允许DDL和系统触发器。当设置隐含参数“_SYSTEM_TRIG_ENABLED”为FALSE的时候，将禁用DDL和系统触发器。所以，当该值设置为FALSE的时候将不能通过这种方式限制登录。

第二种是修改$ORACLE_HOME/network/admin/sqlnet.ora文件，增加如下内容：

之后重新启动监听器即可。这样客户端在登录的时候会报“ORA-12537: TNS:connection closed”的错误。

需要注意的问题：

① 需要设置参数TCP.VALIDNODE_CHECKING为YES才能激活该特性。

② 一定要许可或不要禁止数据库服务器本机的IP地址，否则通过lsnrctl将不能启动或停止监听，因为该过程监听程序会通过本机的IP访问监听器，而该IP被禁止了，但是通过服务启动或关闭则不影响。

③ 当参数TCP.INVITED_NODES和TCP.EXCLUDED_NODES设置的地址相同的时候以TCP.INVITED_NODES的配置为主。

④ 修改之后，一定要重起监听才能生效，而不需要重新启动数据库。

⑤ 这个方式只是适合TCP/IP协议。

⑥ 这个配置适用于Oracle 9i以上版本。在Oracle 9i之前的版本使用文件protocol.ora。

⑦ 在服务器上直接连接数据库不受影响。

⑧ 这种限制方式是通过监听器来限制的。

⑨ 这个限制只是针对IP检测，对于用户名检测是不支持的。

第3种是修改数据库服务器的IPTABLES（配置文件：/etc/sysconfig/iptables）来限制某些IP登录数据库服务器。如下：

则，192.168.59.1这台主机将不能通过1521端口连接到数据库服务器了，会报“ORA-12170: TNS:Connect timeout occurred”的错误。

1.6  参考

1.6.1  MOS

1.6.1.1  Connecting as DBA Does not Fire RAISE_APPLICATION_ERROR in a AFTER LOGON ON DATABASE TRIGGER (文档 ID 226058.1)

APPLIES TO:

Oracle Database - Enterprise Edition - Version 8.1.7.4 to 11.2.0.2 [Release 8.1.7 to 11.2]
Information in this document applies to any platform.
***Checked for relevance on 03-Aug-2016***

SYMPTOMS

TRIGGER AFTER LOGON ON DATABASE does not fire
Login as a user with DBA privileges
ORA-00604: error occurred at recursive SQL level %s
ORA-06512: at %sline %s

CAUSE

 Documented and expected behavior. 

SOLUTION

Oracel Database 11.2:

Oracle? Database PL/SQL Language Reference 11g Release 2 (11.2)
Chapter 9 PL/SQL Triggers
  Exception Handling in Triggers

In most cases, if a trigger runs a statement that raises an exception, and the exception is not handled by an exception handler, then the database rolls back the effects of both the trigger and its triggering statement.

In the following cases, the database rolls back only the effects of the trigger, not the effects of the triggering statement (and logs the error in trace files and the alert log):

    The triggering event is either AFTER STARTUP ON DATABASE or BEFORE SHUTDOWN ON DATABASE.

    The triggering event is AFTER LOGON ON DATABASE and the user has the ADMINISTER DATABASE TRIGGER privilege.

    The triggering event is AFTER LOGON ON SCHEMA and the user either owns the schema or has the ALTER ANY TRIGGER privilege.

Oracle Server 11.1:
Oracle Database PL/SQL Language Reference 11g Release 1
  Chapter: Using Triggers
    Section: Error Conditions and Exceptions in the Trigger Body

If a predefined or user-defined error condition or exception is raised during the execution of a trigger body, then all effects of the trigger body, as well as the triggering statement, are rolled back (unless the error is trapped by an exception handler). Therefore, a trigger body can prevent the execution of the triggering statement by raising an exception. User-defined exceptions are commonly used in triggers that enforce complex security authorizations or integrity constraints.

 
The only exception to this is when the event under consideration is database STARTUP, SHUTDOWN, or LOGIN when the user logging in is SYSTEM. In these scenarios, only the trigger action is rolled back.

REFERENCES

BUG:1415194 - RAISE_APPLICATION_ERROR DOES NOT RAISE AN EXCEPTION INSIDE A AFTER LOGON TRIGGER
http://docs.oracle.com/cd/E11882_01/appdev.112/e25519/triggers.htm#CIHGJCFI 
http://docs.oracle.com/cd/B28359_01/appdev.111/b28370/triggers.htm#autoId33 

1.6.1.2  How to Prevent Users From Log Into a Database Within Defined Periods (文档 ID 220491.1)

PURPOSE
-------
This document explains how to set up the database security so that users cannot
log into the database outside defined time-window.

SCOPE & APPLICATION
-------------------
For DBAs who need to prevent users from log into the database outside defined
time periods.

Use Event Triggers
------------------
If you allow the users to log in the database only from Monday to Friday included,
and from 8AM to 6PM, create an event trigger that checks after logon on
database for each user (except the DBA users) that the connection occurs only
within this timeframe.

Example 1
-------
 1. No check set up yet: any ordinary user can log into the database:

    SQL> connect test_trigger/test_trigger
    Connected.

 2. The DBA creates an event trigger that checks if the connection occurs
    between Monday and Friday , and within working hours: 8AM to 6PM.

    SQL> connect system/manager
    Connected.
    SQL> create or replace trigger logon_trg after logon on database
         begin
          if (to_char(sysdate,'D') not between '2' and '6')
             or (to_char(sysdate, 'HH24') not between '08' and '18') then
             RAISE_APPLICATION_ERROR(-20001, 'You are not allowed to log into
                                              database now.');
      end if;
     end;
     /

    Trigger created.

 3. It is Friday   5PM : an ordinary user can log into the database:

    SQL> connect test_trigger/test_trigger
    Connected.

    It is Monday   7AM : an ordinary user cannot log into the database
    It is Saturday 9AM : an ordinary user cannot log into the database:

    SQL> connect test_trigger/test_trigger
    ERROR:
    ORA-00604: error occurred at recursive SQL level 1
    ORA-20001: You are not allowed to log into database now.
    ORA-06512: at line 3

    Warning: You are no longer connected to ORACLE.
    SQL>

Example 2
-------
Another example to restrict the logon periods for a users so that they can only
access the database betrween the periods to 17:00 - 24:00 daily.
If the user attempts to logon during a period outside of this range his logon
attempt will fail:

    SQL> CREATE OR REPLACE TRIGGER ScottLoginTrigger after logon on scott.schema
         declare
           temp varchar2(50);
           v_time varchar2(50);
           begin
            temp := 'select to_char(sysdate,''HH24:MI'') from dual';
            EXECUTE IMMEDIATE temp into v_time;
            if (to_date(v_time,'HH24:MI') < to_date('17:00','HH24:MI')) then
              raise_application_error (-20001,'SCOTT access is denied until 17:00. The current time is '||v_time,true);
            end if;
            if (to_date(v_time,'HH24:MI') > to_date('23:59','HH24:MI')) then
              raise_application_error (-20001,'SCOTT access is denied because the time is past 23:59. The current time is '||v_time,true);
            end if;
          end;
         /

However, users with ADMINISTER DATABASE TRIGGER system privilege can log into
the database any time.

RELATED DOCUMENTS
----------------- Note:70679.1 How to Audit Logon/Logoff Events with Triggers

1.6.1.3  ADMINISTER DATABASE TRIGGER Privilege Causes Logon Trigger to Skip Errors (文档 ID 265012.1)

***Checked for relevance on 02-Oct-2012*** 

PURPOSE
-------
This bulletin explains which effect the system privilege ADMINISTER DATABASE
TRIGGER has on database triggers when errors are raised.
Similarly, ALTER ANY TRIGGER system privilege causes schema logon triggers to be
skipped on errors.

SCOPE & APPLICATION
-------------------
For DBAs who set up database access control using logon triggers.

ADMINISTER DATABASE TRIGGER Privilege Behavior with Database Logon Trigger
--------------------------------------------------------------------------
Logon triggers can be used to mediate database access: when the restrictive
conditions are not met, an application error with a message is raised that
causes the logon to be denied.

    create or replace trigger on_logon
        after logon on database
        begin
        if USER='TEST' then
           raise_application_error(-20002,'LOGON ERROR',true);
        end if;
       end;
    /

If user TEST connects, he is rejected:

    SQL> connect test/test
    ERROR:
    ORA-00604: error occurred at recursive SQL level 1
    ORA-20002: LOGON ERROR
    ORA-06512: at line 21

    Warning: You are no longer connected to ORACLE.

However, we need to keep at least one user who can still connect when there is
a problem : a fallback mechanism must exist where an administrative user is
exempt from such errors of a prohibited connection. 

Any user granted the ADMINISTER DATABASE TRIGGER system privilege can still
connect : instead of getting the error causing the session to be terminated,
the error is recorded in the alert.log and a trace file in user_dump_dest.

    SQL> connect / as sysdba
    Connected.
    SQL> grant ADMINISTER DATABASE TRIGGER to TEST;
    Grant succeeded.

    SQL> connect test/test
    Connected.                     

In alert.log :

    Fri Mar  5 12:17:08 2004
    Errors in file /ots2/app/oracle/admin/v920/udump/v920_ora_7682.trc:
    ORA-00604: error occurred at recursive SQL level 1
    ORA-20002: LOGON ERROR
    ORA-06512: at line 21    

In trace file :

    *** SESSION ID:(15.76) 2004-03-05 12:17:08.750
    Skipped error 604 during the execution of SYS.ON_LOGON
    *** 2004-03-05 12:17:08.768
    ksedmp: internal or fatal error
    ORA-00604: error occurred at recursive SQL level 1
    ORA-20002: LOGON ERROR
    ORA-06512: at line 21  

The ADMINISTER DATABASE TRIGGER is by default granted to the following users and
roles (are not listed the options' schemas) :

    SQL> select grantee from dba_sys_privs
      2  where privilege='ADMINISTER DATABASE TRIGGER';

    GRANTEE
    ------------------------------
    DBA                            --> role
    SYS                            --> user
    IMP_FULL_DATABASE              --> role
    EXFSYS                         --> user

ALTER ANY TIGGER Privilege Behavior with Schema Logon Trigger
-------------------------------------------------------------
Similarly, if the logon trigger is on SCHEMA and the current user is not the
owner, ALTER ANY TRIGGER privilege is required to be able to connect.

    connect system/manager    

    create or replace trigger on_logon
    after logon on TEST.schema
    begin
       raise_application_error(-20002,'LOGON ERROR',true);
    end;
    /

    SQL> connect test/test
    ERROR:
    ORA-00604: error occurred at recursive SQL level 1
    ORA-20002: LOGON ERROR
    ORA-06512: at line 2

    Warning: You are no longer connected to ORACLE.

    SQL> conn system/manager
    Connected.
    SQL> grant alter any trigger to test;
    Grant succeeded.

    SQL> conn test/test
    Connected.

Triggers owned by SYS and O7_DICTIONARY_ACCESSIBILITY
-----------------------------------------------------

Note that in the above example, the schema trigger is actually owned by user SYSTEM,
this means when user TEST has the ALTER ANY TRIGGER privilege, the trigger can be altered.
As of version 9i, it is O7_DICTIONARY_ACCESSIBILITY parameter that governs/protects the
access to SYS objects, this means that if a schema trigger is owned by user SYS, even if the
user has the ALTER ANY TRIGGER privilege, the logon would still fail as this privilege
is not sufficient to alter SYS objects unless O7_DICTIONARY_ACCESSIBILITY = true.
For security reasons, Oracle recommends that you use this setting only with great caution.

RELATED DOCUMENTS
----------------- Note:120712.1 Database or Logon Event Trigger becomes Invalid: Who can Connect? Note:220491.1 How to Prevent Users From Log Into a Database Within Defined Periods Note:116636.1 ORA-4098 or ORA-4045 logging on to database having AFTER LOGON
                event trigger 

第二章 实验中用到的SQL总结

-------------------------------------------------------------------------

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