sudo

When you install Debian, a default account is created called root. This user has full system access and should be used only for administrative tasks. There are basically no restrictions on what you can do to your system as the root user, which is powerful, but extremely dangerous. To alleviate this risk, we can let some users to execute single commands as root. The command sudo allows you running programs with the security privileges of root.

The benefits of using sudo are the following:

• Nobody needs to know the root password (sudo prompts for the current user's password). Extra privileges can be granted to individual users temporarily, and then taken away without the need for a password change.
• It's easy to run only the commands that require special privileges via sudo; the rest of the time, you work as an unprivileged user, which reduces the damage that mistakes can cause.
• Auditing/logging: when a sudo command is executed, the original username and the command are logged.

Debian allows users that are member of a group called sudo to run commands with the help of the command sudo. In order to add a user to the group sudo:

• Run the following command as a root user: gpasswd -a <userame> sudo (where <username> is the real username of the user you want to add to the group sudo)
• If the user is logged on the system, he/she has to logout and login again in order to be effectively part of the group sudo.

The moment you are member of group sudo, you can run commands with the root privileges just adding sudo before the command. The system will ask for your password (no the root password but your standard user password).

The default timeout of sudo is 5 minutes; that is, Linux will remember your password for 5 minutes by default.

In order to check if you are member of the group sudo run the following command: id. This command shows a list of groups you are member of. If 27(sudo) appears then,you are member of the group.

Good practice:

• Use sudo only when needed. Run everyday tasks as a normal user and add sudo only for commands that require administrator privileges, such as changing network settings or installing software.
• Be careful with what you run. A command executed with sudo has full control over the system, so a typing mistake can delete files or break the configuration. Read the command carefully before pressing Enter, and never paste commands from sources you don’t trust.

IMPORTANT: From now until the end of the academic year, use the sudo command for administrative tasks and DO NOT LOG IN to the system as the root user.