SSH and user account without password

Highly insecure!

Step 1: Create user with no password

Create a user with a password, and delete it later ([1]):

root@inabox:/home/ina# adduser test
[...give a password...]
root@inabox:/home/ina# passwd -d test
passwd: password expiry information changed.

Step 2: Let the user log in

In /etc/pam.d/common-auth:

# here are the per-package modules (the "Primary" block)
auth    [success=1 default=ignore] nullok_secure

Change nullok_secure into nullok ([2]).

Step 3: Let the user log in over ssh

In /etc/ssh/sshd_config:

# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no

Hey, be optimistic, make that no a yes ([3]), and reload the config of sshd:

root@inabox:/home/ina# systemctl reload ssh.service