Thank you guys
I understand it clearly now.

Hi everyone

I know what a 51 % miner attack is, but does a 51 % node attack exists?
If i understand it correct nodes check transactions if thy are valid. if some node doesnt follow the rules , it got kicked from the network.
But if some party owns 51 % of the nodes, can they change the rules ? can they accept false transactions? Or Can they only make a hardfork because they dont follow the rules anymore?

thank you in advance
Qosmos