Transclusion: Debian: Logging In

Use the following username to login:

Account with administrative privileges:

User: root

To login into the Linux system, you may use a serial console, or connect through the network (ssh), or use a keyboard and display.

root password

This Debian rootfs comes without default root password.
The root password has to be set at the very first login:

Debian GNU/Linux stretch/sid cl-rootfs ttymxc0

cl-rootfs login: root
You are required to change your password immediately (root enforced)
Enter new UNIX password: