Some years ago our company site was hosted by a prick who knew nothing and started to pretend the server got a virus or whatever.

I tested their server and figured out they did not have any firewall policies going on like mitigation of ssh brute force.

It was at this time I learned about SYN flood, and boy I flooded that port 80 of them.

The company site went down for as long as I wanted.

It was great because now we manage it in house and never had a problem anymore.