How to access Oracle database over network?

Whenever you are sufering with this kind of errors while creating remote access for you database, do following things before.

1. Create a Listener using Net Manager tool of Oracle or create it Manually.
2. After generating Listener, check out "listener.ora" [Located : ORACLE_INSTALLED_DIR\product\11.2.0\dbhome_1\NETWORK\ADMIN]file, for your entry. (is there any Entry for the Listener which you have created just before. If you found your Entry than and than do next steps otherwise do it from FIRST step.)
3. If you found the Entry for your Listener, Open Command Prompt and fire command lsnrctl status. This will give you all currently running Listeners List, find out the one which you created just before.
4. Check out the Host Name and Port Number for your Listener.
5. Generate the Connection String as per the details you found in lsnrctl status
6. Connect with Database, and You can access the Database from anywhere in your Network.

Enjoy the Things, Some challenges needs Afforts, Once you fall back from it, it will be never solved.

I am really thankful to those all Guys who answered and Commented to this Question, this all Material made my Challenge easy..

Thank You @Alex, @ Lalit, @TenG and @S.KrishnaThank You so Much Guys.

If your host name and port number is listener then You could try this option by enabling port number in firewall settings.

Opening Ports in Windows Firewall

• Open the Control Panel. ...
• Open Windows Firewall. ...
• Click the Advanced Settings link. ...
• Select "Inbound Rules". ...
• Create "New Rule" under "Inbound Rules". ...
• Select "Port" from the first screen of the wizard. ...
• Choose TCP or UDP. ...
• Enter in the port range. ...
• Finish the wizard.

Create an entry in TNSNAMES.ORA file on the system from which you are trying to connect to the database. (TNSNAMES.ORA is located in ORACLE_INSTALLATION_PATH/Network/Admin/ folder)

Sample entry:

DB_HOST_NAME =  (DESCRIPTION =    (ADDRESS = (PROTOCOL = TCP)(HOST = DB_HOST_NAME)(PORT = 1521))    (CONNECT_DATA =      (SERVER = DEDICATED)      (SERVICE_NAME = XE)    )  )

If you have more than one Oracle clients installed, you might need to update this in all those TNSNAMES.ORA