Linux Enable user with blank password.

Create user on linux.

sudo useradd user1

By default user is created and is disabled for login till we set the new password. Execute following command to verify and clear the password from linux user user1.

sudo grep user1 /etc/shadow

sudo passwd -d user1

By default ssh is not allowed to login with blank password. We need to enable it with following parameter.

PermitEmptyPasswords yes

Restart ssh service to reflect the change.

/etc/init.d/sshd restart

Now you may login without password prompt.

ssh user1@10.10.10.250

Removing password from user and allowing Empty password to login via ssh is great threat. Enable it at your own risk and do not configure it unless it is required and understood properly.