Managing Users and Permissions

In the previous chapter, we set up our very own Ubuntu Server installation, and we can now learn how to maintain it, starting with a look at managing who is able to use our server.

As administrators of Ubuntu servers, users can be your greatest asset and also your biggest headache. During your career, you’ll add countless new users, manage their passwords, remove their accounts when they leave the company, and grant or remove access to resources across the network. Even on servers on which you’re the only user, you’ll still find yourself managing user accounts, since even system processes run as users. To be successful at managing Linux servers, you’ll also need to know how to manage permissions, create password policies, and limit who can execute administrative commands on the machine. In this chapter, we’ll work through these concepts so that you have a clear idea of how to manage users and their resources.

In particular, we will cover:

• Understanding the purpose of users and groups
• Understanding when to use root
• Creating and removing users
• Understanding the /etc/passwd and /etc/shadow files
• Distributing default configuration files with /etc/skel
• Switching between users
• Managing groups
• Managing passwords and password policies
• Configuring administrator access with sudo
• Setting permissions on files and directories

In the first section, we will have a quick discussion about the nature of managing users.