Test connectivity on Linux

Using curl

curl -v telnet://host:port

Using netcat

nc -z -v host port

cURL file send to Oracle cloud

curl --write-out '%{time_total}' -X POST --data-binary "@5M.csv" -H "Content-Type:text/csv" --user <user>:<password> "https://....adb.us-ashburn-1.oraclecloudapps.com/ords/<user>/huge_csv/batchload?batchRows=5000&errorsMax=20"

Taken from here

USE_SHARED_SOCKET

For old versions as pointed in the note Troubleshooting Connectivity Issues From a Remote Client to a Database (Doc ID 271852.1)

For 9.2 and below, if the Operating System is Microsoft Windows NT,
and you are using the dedicated server connection, a spawned Oracle
thread communicates with the client through a randomly allocated port
(called a REDIRECT). To force the oracle process to communicate only
through the port in which Listener is listening, set the key,
USE_SHARED_SOCKET = TRUE, in the Windows Registry
NOTE:
This is no longer the case with 10g and up as a REDIRECT does not take place for DEDICATED connections.

Или, если верить ноте 124140.1, начиная с версии 10.2

This technique only involves the version 8.1 to 10.1 Oracle Database versions. From 10.2 onward the default changed to allow port sharing.

Причина этого

Microsoft WINSOCK V1.1 API did not allow one process to pass a TCP socket to another process and as a result did not allow port sharing like on UNIX systems

Знание уже абсолютно бесполезное, ибо:

1. С версии 10.2 USE_SHARED_SOCKET=TRUE в реестре или переменной окружения
2. Уже 100 лет не видел Oracle на Windows за исключением собственного ноута