My Server get attack by bot and tried to send an empty message see this log https://pastebin.com/EbG9sHnn them send an empty message for 10,000 msg in 1 second I try to fix this for a long time modify NoCheatPlus about Captcha,FastChat using plugin Antijoinbot it can help a little bit such If a bot spam chat [NoCheatPlus will detect and use command switchantijoinbot (authme)] but it can't help empty message and it's too fast it very fast 10,000 msg in 1 sec so my server crash suddenly How to fix this problem? Have anyone can help me? Sorry if you don't understand some word. I don't good at English.
in your server.properties, you set online-mode to false. Set it to true and the bots can't attack your server
