How to connect with System.Data.OracleClient to oracle db with windows authentication?

Question

With Oracle SQL Developer I can put / -character to Username and leave password empty and I get connected. I have OP$MYWINDOWSUSERNAME user created in database.

EDIT: SQL Developer does not work if I check OS Authentication-checkbox (empties and disables username + pwd). Moreover Preferences->Database->Advanced->Use Oracle Client is unchecked so I guess what SQL Developer does or doesn't has very little to do with my System.Data.OracleClient.OracleConnection problem.

However when I try to form connection string like this:

string.Format("Data Source={0}; user id=/;password=;Integrated Security=yes", dbName);

I get ORA-01017: invalid username/password: logon denied

with

string.Format("Data Source={0}; user id=/;password=;Integrated Security=no", dbName);

I get ORA-01005.

With

string.Format("Data Source={0};Integrated Security=yes", dbName);

I get ORA-01017: invalid username/password: logon denied

With

string.Format("Data Source={0}; user id=/;", dbName);

I get ORA-01005

With

string.Format("Data Source={0};User Id=/;Integrated Security=yes;", dbName);

I get ORA-01017

Both OracleConnection in my program and Oracle SQL Developer work when I specify Username and password.

EDIT: This works with

string.Format("Data Source={0};Integrated Security=yes", dbName);

when sqlnet.ora line

SQLNET.AUTHENTICATION_SERVICES= (NTS) 

is changed to

SQLNET.AUTHENTICATION_SERVICES= (NONE)

If somebody writes short answer what is happening and why, i'm happy to grant bounty to him/her.

Answer 1

In short, it's the Windows native operating system authentication which is indicated by NTS.

Once NTS is specified, oracle client identifies the username as workgroup\username or domain\username which does not match your OP$MYWINDOWSUSERNAME database user

In order to have it working with NTS option, you need to include domain/workgroup name in your db username:

CREATE USER "OPS$<DOMAIN_NAME>\<OS_USERNAME>" IDENTIFIED EXTERNALLY;

oracle support document 750436.1 confirms this with detailed steps.