Limiting logins from client?

[Triceps]

Hello all.
So i got this problem on my server - users can enter acc and password as many times as they want and without delay, thus making brute-forcing easy..
I couldn't find this setting documented any where, also, search on forums was not successful.
Does anyone know how to limit it? (server side) Any delay between the logins, or a temp ban after some unsuccessful login attempts?

Thanks in advance!