1. You can test Moodle's connectivity with Turnitin, and see if both sides are communicating without any problems, by navigating to Site administration > Advanced features > Plugins > Turnitin Assignment 2.
2. To check the communication with Turnitin click on the Test Turnitin Connection link.
3. If you click on the Test Turnitin Connection link, Moodle will try to access Turnitin. If Moodle successfully connects to Turnitin, A green box will appear telling you Moodle successfully connected with Turnitin. If you receive an error message please check the configuration data that was entered and fix any errors.
The Show Data Dump and Save Data Dump links are useful for troubleshooting and may be referred to by Turnitin support. The Data dump tracks all Moodle communication with Turnitin. For example, the name and dates of each Turnitin assignment that was created within a course.
The Unlink Users link can be used to reset links between Turnitin accounts and Moodle accounts.
If you encounter connectivity issues while using the Turnitin Moodle Direct integration (error: Turnitin API Base URL incorrect or unavailable, or error: Double check your API URL setting) this could be related to a CA certificate being unavailable to cURL. Enabling diagnostics mode in the Turnitin plugin and viewing the Turnitin comms logs will identify if this is the case.
The Moodle Direct plugin uses the server operating system's implementation of cURL. If cURL has an out of date (or no) CA certificates, the interaction with Turnitin will fail due to cURL performing peer SSL certificate verification and not being able to verify the Turnitin SSL certificate.
Until cURL 7.18.0 some CA certificates were provided, but after 7.18.0 no CA certificates have been provided at all. Because of this, the Moodle server administrator would need to ensure that an up to date CA certificate bundle is used.
CA certificates are distributed in the ca-certificates package. Gentoo servers provide them via the app-misc/ca-certificates ebuild. It's also a good idea to make sure that the OpenSSL libraries (libssl) and cURL libraries (libcurl) are up-to-date on your server.
You will also need to place a file with the Bundle of CA Root Certificates (downloadable from http://curl.haxx.se/ca/cacert.pem) on your webserver and make a curl.cainfo reference to this file in your php.ini.
Please see point 4 within the link below which describes where to put/how to name the CA certificate bundle.