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Changes to the Similarity Check service - some subscribers need to whitelist an additional IP address by 31st October 2021

The Similarity Check service gives Crossref members reduced rate access to the iThenticate service from Turnitin. You receive this reduced rate access as you contribute to the iThenticate database of published content by providing full text URLs for this service in the metadata you register with us. If your content is behind access control and readers have to sign in before they can access your content, you will have whitelisted Turnitin’s IP address when you joined the service to let them index your content.

Turnitin will be changing their IP address on 31st October, so you’ll need to whitelist that new IP address before then to remain eligible for the service. Please note, you need to whitelist that IP address in addition to the current one. We will confirm in the future when the old IP address has stopped being used.

Please whitelist the new IP range to as well as the existing range to

Who needs to do this?

  • If your content is available to readers without them having to login, you don’t need to take any action.
  • If your content is behind access control or a paywall and readers can only access the content by logging in, you will need to add the additional IP address. Many of the platform providers are already looking after this for their clients, and we will keep this post updated with the platform providers who have confirmed this. If your provider isn’t listed or you aren’t sure, do check with your provider. If you aren’t using a platform, please check with your IT team.

UPDATE — Atypon, Highwire Press and Silverchair have informed us that they will be making these changes on behalf of their customers.

If the content is available to readers without their having to log in, is it still advised to whitelist the IP addresses to avoid triggering DDoS controls?

Hello @rhiannon-ppl

If your content is available to readers without their having to log in, you do not need to do anything.



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