How to create a rule to block traffic where “Browser = Unknown” and

We experienced a heavy DDOS attack on our website.

For all suspicious traffic the browser is unknown and is OS unknown.

We like to create a rule where traffic is blocked when “Browser = Unknown” and where “OS = Unknown”. How to do this? FYI: we have a “Pro” account.

Pretty sure, Unkown just means that Cloudflare doesn’t recognize / is able to parse the user agent.

This has come up before and no solution of blocking.

Thank you for your reply. I truly do not understand why CF does not offer the possibility to setup a rule “When Cloudflare doesn’t recognize / is able to parse the user agent” → block it. I think that would work for us and would solve our main issue.

Hi @cityoflove

I would not recommend that you block unknown browser. This is a term used by Cloudflare for all the “small” browser providers. Cloudflare collects all these browser providers under the term unknown browser, but this is still legit users.