ERPstuff - Oracle EBS Community

I just installed Oracle EBS 11i on RHEL AS4. I have a laptop(windows running oracle client tools) that I use to connect all my oracle-db instances. However, my newly installed apps 11i won't let me connect using sqlplus or any other client from my laptop (or any other client machine for that matter). Again, I am trying to access the tables not the forms interface using jinitiator. Here is the error message I keep getting: "TNS 12537 Connection closed"

I see that discoverer related processes started when I started the apps. Is there a discoverer admin console that I can use? Also can I install discoverer plus or discoverer desktop to connect to the descoverer running on the apps server? Can I view the existing Discoverer reports using a browser?

I appreciate your responses in advance.

the following parameters to your sqlnet.ora file:
tcp.validnode_checking = yes
tcp.invited_nodes = (www.aq.com,172.16.1.4)
tcp.excluded_nodes = (199.16.1.21)

The first line enables this features. The invited nodes is a list of the hosts, either DNS name or IP address, that are allowed to connect. The excluded nodes is a list of hosts that are not allowed to connect to the database.
Note: The tcp.invited_nodes parameter takes precedence over the tcp.excluded_nodes parameter if both lists are present.

Note 2: For Oracle 8i and below these parameters needs to be set in a protocol.ora file on your server (located in $ORACLE_HOME/network/admin or $TNS_ADMIN).