On VDS attack with falsified IP, how to protect yourself?

Question

System administration

On a certain port there is a flood from falsified IP, how to protect and filter connections?
And will the method help - skip IP the second time?

Answer 1

1. iptables
2. On what port?
2.1 If 80 - read how to protect yourself from DDOS attacks.
2.2 If 22, change the ssh port and you will be happy.