useradd

useradd(8) - Linux manual pageman7.org

useradd - create a new user or update default new user information

Example

Suppose we want to create a user named tunneluser that is used primarily to accept SSH connections (eg. for tunneling, etc.). This user should have no access to the shell console.

$ useradd tunneluser -m -d -/home/tunneluser -s /bin/true
# or 
$ useradd tunneluser --create-home --home-dir /home/tunneluser --shell /bin/true

• -m/--create-home : create the user's home directory if it does not exit

• -d/--home-dir HOME_DIR : the new user will be created using HOME_DIR as the user's login directory

• -s/--shell : sets the path to the user's login shell

  • the value /bin/true simply returns true by doing nothing, successfully

  • this is useful to prevent remote users who connects via SSH, from accessing the shell and perform actions such as file transfers (SCP) or command execution.

true(1) - Linux manual pageman7.org

Next, we have to make sure to set a strong password to prevent anyone from simply connecting to our machine via SSH:

$ passwd tunneluser