I recently revised a plugin I wrote about 9/10 years ago (when nop MVC arrived) to work with v3.8, that replaced the pre 2.0 banned ip list. It morphed into something that also blocked spam registrations and messages and added them to a reject/banned ip list.
Would this be something of interest to the community? I'd need to make a version for other builds and it needs some refinement before it would be appropriate for release, so I'm seeing whether it's worth it for me to develop it further. I don't know whether this would be a paid for or free plugin at the moment. I like the idea of releasing a free basic/evaluation/community version and a full version with a few more bells and whistles, plus support for larger organisations and sites.
I don't think there's anything available that does this for nopcommerce or manages banned ip addresses?
Here's the basics of how it works:
It checks the registration process for certain criteria in the form content and creates a score. If the score is over a certain value, it adds the IP to a banned list and does some logging if the option is selected. It then redirects to a website of your choice. the default is SpamHaus, which I think is quite amusing in itself.
You can also manually add IP addresses to the list.
There is also a feature so messages (from contact etc) can be checked against SpamAssasin and rejected and also logged and added to the banned ip list (this needs some work, as the api has changed since I originally did this).
In the week since I put this on a site, spam registrations/users accounts have gone from 100/200 a day down to zero.