As of NEMS 1.3 the default username for initial setup is nemsadmin. This is used to sign-in to your NEMS server (over SSH or keyboard connected to your NEMS server) only until you run nems-init.
Once your nems-init process is complete, you will need to instead sign-in as your newly created account (which you specify during nems-init).
When you initialize NEMS, you will provide a password for the NEMS web interfaces. This username/password will be what you use to access NEMS features (eg., nCONF, Nagios Core, NagVis, Check_MK, Samba, Webmin, SSH, etc.).
If you are on an old version 1.0-1.2.x of NEMS, you will instead use the following credentials: