Aim is to add another user which can be used for ssh access.
Then allow to switch to the default user tc.

With the default sshd configuration it is not allowed to login to a passwordless user.
User tc has no password set by default and I prefer to keep it passwordless.
As a next step public-key authentication can be enabled to directly login to user tc.

• Add a user:
  • sudo adduser <username>

• From user tc login as root and make <username> a sudo user:
  • sudo su
  • chmod 660 /etc/sudoers
  • vi /etc/sudoers
  • add:

     <username> ALL=NOPASSWD:ALL 

  • chmod 440 /etc/sudoers
  • exit
  • sudo vi /opt/.filetool.lst
  • add:

     etc/sudoers 

  • backup

• Switch to user tc after login with user <username>
  • sudo su
  • su - tc
    or
  • sudo su - tc