SQL Developer: Failure -Test failed: IO Error: Network Adapter No Conn

Question

SQL Developer: Failure -Test failed: IO Error: The Network Adapter could not establish the connection
Hi,
and sorry this is a really common questions and yes I did do a search, but I don't understand it.
First let me just tell you that Oracle 11g is installed on my second laptop on the same Network.
Secondly I can connect to the Database using Oracle SQL Developer on the laptop Oracle 11g is installed on.
The problem is I want to connect to the database on my main Laptop.
I put in the correct details Hostname 192.168.0.8 ( this is the laptop oracle is installed and running on)
Port 1521
SID dbarudu
****** YES I HAVE PORT FORWARDED
****** YES I HAVE ALLOWED 1521 on the FIREWALL
****** YES I HAVE EVEN SWITCHED OFF THE FIREWALL
Now one more thing you should know ... I don't know nothing about Oracle Servers ok.... so I have just installed Oracle 11g Enterprise and thought done it should be working now.
I just need to use oracle db for a project.
So keep in mind I am a total noob and terms like TNSPING etc mean absolutely nothing to me.
So please help, but help with step by step guide on how to get Oracle to let me have access from another computer.

Answer 1

If the Listener is working, then you should not get the error SQL-Developer error you are reporting.
The listener typically runs using the hostname and port 1521. This means it opens tcp port 1521 on all IP addresses of that platform.
The database server by default will register itself with the local listener. Thus the listener will know the database SID, the database services, whether there are dispatchers to support shared server connections and so on.
The client side needs simply to specify 3 pieces of data to connect:
- the IP of the database server
- the tcp port of the listener
- a database identifier (such as Oracle SID or service name) to connect to
It is really that simple.
If this does not work, the problem falls into 2 broad categories:
a) incorrect installation and configuration of the Oracle software (the out-of-the-box install works unless messed up)
b) some kind of networking issue
To troubleshoot any problem means reducing the complexity of the problem, eliminating multiple moving parts and focusing on specific ones, in order to isolate the problem.
For your problem, this will go something as follows:
- does the listener run? (check if the service is running and whether tcp connections are accepted on the listener port - telnet can be used for the latter)
- does the database successfully registers itself with the listener? (check the services command of the listener and relevant db initialisation parameters)
- does a local TNS (tcp network) connection work on that server? (use SQL*Plus and test on that platform client-server connectivity via tcp to the listener)
- does the client platform have connectivity with the server platform? (use ICMP and telnet to test)
- repeat the TNS test on the client platform using the same working TNS tested on the server platform
Do not use JDBC to test the connection - keep it simple and use sqlplus and the standard Oracle Call Interface (OCI). A full client version of the OCI plus sqlplus can be downloaded under the Oracle InstantClient downloads.
Finally - if you expect to simply install and use Oracle, then use the correct version. Oracle Express Edition aka Oracle XE. Installs and works out-of-the-box. The only manual config change to make is (as far as I recall) to run the listener on all IP addresses of that platform. And this required editing the listener.ora file, changing the HOST parameter and restarting the listener.
Also keep in mind that you have not presented an Oracle error code and Oracle error message. But a client application error message. And that message is pretty much meaningless - it does not point to a specific Oracle networking or Oracle server problem. To diagnose that, we expect a TNS or ORA error number.