Blocking Spam Comments IP

Is there any way I can block certain, specific IP addresses of the incoming spam on my comments on my posts?

I’m aware you can add filters to spot spam bots, scripts, etc. with plug-ins or add-ons but I’d really prefer not to (without it, it is more encouraging for anonymous users to comment and get discussion going…). (Plus I’ve finally designed it down to where I’m comfortable with the comments section of my pages.)

I receive junk from the same one or two entities with just gibberish and/or web links. How do I block them? I’ve deleted or marked-as-spam to over a dozen in the last day, only!, all of a sudden!, can anyone help??

Thank you so much,