Yuk Ding, from Microsoft, provided this Server Fault link: How to get IP address, which contains a couple options for recording the login IP addresses that I have been looking for.
It does not appear that this information is available in a default log, which I was looking for. It would appear that an event listener must be created to log the IP addresses.
PowerShell Script to Read IP Addresses
netstat -n | find ":3389" | find "ESTABLISHED">>%logfile%
@chaz provided a useful PowerShell script to read the IP addresses associated with the failed login attempts, click here.
Windows Firewall Script To Block IP Addresses
I found a very useful PowerShell script for automating the task of blocking IP addresses in Windows Firewall. The script was written by Jason Fossen.
The following is from Jason's website here.
The host-based Windows Firewall is easily managed through scripts and the NETSH.EXE command-line tool. This article is about a simple PowerShell script which can create rules to block inbound and outbound access to thousands of IP addresses and network ID ranges, such as for attackers and unwanted countries.
To get the script, download the SEC505 zip file here or from the Downloads page, open the zip and look in the "Day5-IPSec" folder for the script named Import-Firewall-Blocklist.ps1 (and the sample BlockList.txt file too). Like all the other scripts in the zip file, this script is free and in the public domain.
Integrated Scripts with C#
I wrote a C# program to integrate the scripts, which reduced daily failed logins of 160,000+ to a small trickle.
Hope this short write-up/links provide some help to others struggling with the same issue. Contact me if you have issues/questions.