 <p>Basically <code>nscurl --ats-diagnostics &lt;url&gt;</code> just tries all possible variants of connection to server and responses with PASS/FAIL results for each test. You should just find which tests pass for your server and set ATS configuration accordingly.</p> <p><a href="http://useyourloaf.com/blog/app-transport-security.html" rel="nofollow">Here's</a> a good article on ATS and checking server compliance, it also contains an nscurl example.</p>