You want to use Linux and OpenSSH to automize your tasks. Therefore you need an automatic login from host A / user a to Host B / user b. You don't want to enter any passwords, because you want to call ssh from a within a shell script.
NTRadPing is a useful tool for testing installations of your RADIUS servers. Through NTRadPing you can simulate authentication and accounting requests and send them to the RADIUS server making NTRadPing act as a NAS client.