下面是一个触发器的例子：

复制代码 代码如下:

create or replace trigger logon_ip_control
after logon on database
declare
ip STRING(30);
user STRING(30);
begin
SELECT SYS_CONTEXT('USERENV','SESSION_USER') into user from dual;
SELECT SYS_CONTEXT('USERENV','IP_ADDRESS') into ip from dual;
if user='EPAY_USER'
THEN
IF ip not in ('192.168.219.20','192.168.219.22')
THEN raise_application_error(-20001,'User '||user||' is not allowed to connect from '||ip);
END IF;
END IF;
end;
/

该触发器对用户EPAY_USER进行了IP限制（只允许'192.168.219.20','192.168.219.22'，如果需要设置IP段，用%或?代替即可，如'192.168.219.%‘）。
下面看几个例子测试一下：
1）从非允许IP地址登陆 （192.168.219.21），连接失败

复制代码 代码如下:

[oracle@lxdb2 ~]$ sqlplus epay_user@pri
SQL*Plus: Release 11.2.0.3.0 Production on Wed Jul 3 19:23:48 2013
Copyright (c) 1982, 2011, Oracle. All rights reserved.
Enter password:
ERROR:
ORA-00604: error occurred at recursive SQL level 1
ORA-20001: User EPAY_USER is not allowed to connect from 192.168.219.21
ORA-06512: at line 10

2）从允许IP地址登陆（192.168.219.22），连接成功

复制代码 代码如下:

[oracle@lxdb1 ~]$ sqlplus epay_user
SQL*Plus: Release 11.2.0.3.0 Production on Wed Jul 3 11:24:25 2013
Copyright (c) 1982, 2011, Oracle. All rights reserved.
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

3）从本地登陆(192.168.219.23）不受IP限制影响，连接成功

复制代码 代码如下:

[oracle@lxdb1 ~]$ sqlplus epay_user
SQL*Plus: Release 11.2.0.3.0 Production on Wed Jul 3 11:24:25 2013
Copyright (c) 1982, 2011, Oracle. All rights reserved.
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options