title: How to connect with System.Data.OracleClient to oracle db with windows authentication?
body: <p>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.</p>
  
  <p>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.</p>
  
  <p>However when I try to form connection string like this: </p>
  
  <pre><code>string.Format("Data Source={0}; user id=/;password=;Integrated Security=yes", dbName);
  </code></pre>
  
  <p>I get ORA-01017: invalid username/password: logon denied</p>
  
  <p>with </p>
  
  <pre><code>string.Format("Data Source={0}; user id=/;password=;Integrated Security=no", dbName);
  </code></pre>
  
  <p>I get ORA-01005.</p>
  
  <p>With </p>
  
  <pre><code>string.Format("Data Source={0};Integrated Security=yes", dbName);
  </code></pre>
  
  <p>I get  ORA-01017: invalid username/password: logon denied</p>
  
  <p>With </p>
  
  <pre><code>string.Format("Data Source={0}; user id=/;", dbName);
  </code></pre>
  
  <p>I get ORA-01005</p>
  
  <p>With</p>
  
  <pre><code>string.Format("Data Source={0};User Id=/;Integrated Security=yes;", dbName);
  </code></pre>
  
  <p>I get ORA-01017</p>
  
  <p>Both OracleConnection in my program and Oracle SQL Developer work when I specify Username and password. </p>
  
  <p>EDIT: This works with </p>
  
  <pre><code>string.Format("Data Source={0};Integrated Security=yes", dbName);
  </code></pre>
  
  <p>when sqlnet.ora line</p>
  
  <pre><code>SQLNET.AUTHENTICATION_SERVICES= (NTS) 
  </code></pre>
  
  <p>is changed to </p>
  
  <pre><code>SQLNET.AUTHENTICATION_SERVICES= (NONE)
  </code></pre>
  
  <p>If somebody writes short answer what is happening and why, i'm happy to grant bounty to him/her.</p>