Finding an Oracle database server on the network is best achieved by doing a TCP port scan, unless of course you already know where it is. Oracle and its peripheral processes listen on so many different ports, chances are that one of them will be on the default port even if most of them aren't. The following list details some common Oracle processes and what ports they can be found listening on.
The common ports are
Once the Oracle database server has been discovered the first port of call is the TNS Listener. You need to get some information before continuing, such as the version, the OS, and database services. The Listener control utility can be used to get this information. Run the utility from a command line and as the first command set the Listener you want to connect to:
LSNRCTL> set current_listener 10.1.1.1
This will direct all commands to the TNS Listener at IP address 10.1.1.1. Once set, run the version command:
LSNRCTL> version Connecting to (DESCRIPTION=(CONNECT_DATA=(SID=*)(SERVICE_NAME=10.1.1.1))(ADDRESS=(PROTOCOL=TCP)(HOST=10.1.1.1)(PORT=1521))) TNSLSNR for 32-bit Windows: ...