Lesson 1

Date: 1/18/2017
User accounts, files and directories, processes, system commands.
Linux System Administration


User accounts



  • In order to login to a system a user has to authenticate with his/her credentials: user name and password.

  • Authentication types:
      local (password/shadow/group) and
      Domain based (NIS, Kerberos, LDAP).
  • For local authentication, a user should have an account on the system.

  • Entry in /etc/passwd: mike:x:1001:1001:Michael Whites:/home/mike:/bin/bash
  • Entry in /etc/shadow: mike:$1$zXCV7fz8ii84grbZhj:14087:0:99999:7:::
  • Entry in /etc/group: mike:x:1001:mike
                                    admin:x:112:hostadm,mike

  • Accounts can be created only by a superuser (root).

  • Commands to create user accounts:
    adduser (interactive command)
    useradd (can be included in a script).

    Exercise
    Create a new user account by following the instructor.

    Become root:
    sudo -s
    
    Create a new user account, mike
    adduser mike
    
    Verify the account existence:
    id mike
    finger mike
    
    Change password of the user
    passwd mike
    

  • Reference: User accounts and Ownerships



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