Block by IP

My site is under ddos now. How can I see IP addresses that attacking me in cloudflare? I didn’t find the list of IP in their interface

First, switch to “I am under attack”. Then, check the log files on your server.

log files contains only cloudflare’s IP addresses

That is because you havent rewritten the IP addresses. In that case it will be difficult to determine the actual address. Reconfigure your webserver to show the client addresses instead -> (use mod_remoteip if you are on Apache).