How to crash a server sponge ? (by other players)

Hello, yesterday my server was the victim of an attack to make it crash.

How did the person proceed ? This person don’t have a mod installed, spam connexion in my server spongeforge (very spamming). And my server crash.

Check this log : https://pastebin.com/raw/GB7x3zHE

But, there is not a 1/10 of the connections he has had in total in this pastebin.

How to resolve this problem ?

Thanks you (sorry i’m french ^^)

He likely was attempting to do a similar attack to DDOS. Typically, your best bet in this case is to set your firewall(s) to block their IP addresses. Some firewalls allow you to set up rate limited requests, which might also help