Listener valid node checking

Valid node checking is the one of the listener secuirty feature. I thought may be very lesser known this feature. What purpose of this feature use, this feature uses If you configuring the the set of invited or exluded nodes, you can take control of which hosts are allowed to connect your database. You can add it hostnames or ip address in sqlnet.ora file.

In other cases it can be more complex, particularly when a single database is hosting several applications.There will be some cases where a database must accept connections from a large number of hosts, when the list of hosts that connect is constantly hanging, or even some organizations that change both IP addresses and hostnames for their machines on a somewhat random basis. For these systems,Valid Node Checking is not a viable feature.

If you think your database may connect few client hosts, you can add this feature in sqlnet.ora file. this feature restricted to connect the database from other client hosts.

Let’s See ,

Database Server , I just configured following entries in sqlnet.ora file.

tcp.validnode_checking = yes

 

 tcp.invited_nodes = (siebelpoc)

Reload listener

lsnrctl>reload

From client host :

[oracle@siebelpoc ~]$ export ORACLE_SID=testdb 
[oracle@siebelpoc ~]$ sqlplus system/Admin123@testdb

SQL*Plus: Release 11.2.0.1.0 Production on Sun Feb 26 11:02:48 2012

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select name from v$database;

NAME --------- TESTDB

I can able to connect.

Again I just edited invited nodes in database server sqlnet.ora file

tcp.validnode_checking = yes

 

tcp.invited_nodes = (siebel)

Reload listener

lsnrctl>reload

From client machine,

[oracle@siebelpoc ~]$ sqlplus system/Admin123@testdb

SQL*Plus: Release 11.2.0.1.0 Production on Sun Feb 26 11:05:36 2012

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

ERROR: ORA-12537: TNS:connection closed

Now I can not able to connect the database from client hosts because of i changed invited node in sqlnet.ora file.