NIS is to setup a networked user authentication systems for Debian OS. It was the old software that was then replaced by LDAP software. This section guides you on how to harden Debian by not using NIS.
These are the identified threats related to Debian software.
NIS is deprecated but used to manage networked credentials.
NIS is transmitting sensitive data like password in plaintext.
Here are the list if actions to counter the issues.
LDAP exists for a reason. Use LDAP instead.
That's all for hardening Debian by not using NIS.