This tool allows to find AS400 usernames.
The existing NSE script that works on Mainframe does not work on AS400 (there is no TSO on AS400). So I coded this one to be able to bruteforce AS400 username.
There is a limit of 3 tries per user (most of the time). Keep that in mind.
It works on linux and windows as well.
You can test a single username:password
Or a predifined list