Possible brute force IP attack - how to block international access

[SteelSignature]

After attempting the use of a plugin, we're now receiving regular failed logins with international IP addresses. The emails look like below:

Quote

A recent login attempt failed. Details of the attempt are below.

Date/Time: 27/10/2019 21:39:03
Username: ' or ''='
IP Address: 104.248.199.155
Hostname: 104.248.199.155

How do you ban all IP addresses outside a region (United States)? (Essentially ban all IP + White List only US IP) The system allows ranges, but I do not want to create 500 different rules for all the various countries and IP ranges.

If I'm reading this wrong and there's a better explanation, please learn me something 😉

[Remitur]

You need to do it server-side.

The fast and easy way to fix it at WHMCS-level: enable 2FA