Do I need a Firewall for SSH when authorizing only with an RSA key?

Question

SSH

Hello.
Does it make sense to use Firewall for SSH when using an RSA key? I can not understand whether this will add problems or increase the security of the server. Explain, please.

Answer 1

Well, what tasks will the firewall perform?

Answer 2

Needed of course. Drive password pickers for the root user (oddly enough, there are a lot of them) :)