I configured UPS on TrueNAS Core (TrueNAS-13.0-U6.2).
All works okay but I discovered that I can connect witthout password!!
If I login with telnet
telnet 192.168.1.1 3493
And I give the command
LIST VAR ups
I get the response without the need to login. 
My upsd.users if really simple:
[upsmon]
password = ********
upsmon master
I find no way to force using a password to get the data. (2 hours searching everywhere…)
Any suggestion?