On any GNU/Linux system, the root user It's that figure everyone respects (and you should be a little afraid of them). It's the equivalent of the "administrator" in other systems, with the difference that here the permissions are so broad that a poorly typed command can wreck the system in seconds. To fully understand what root is, what root privileges are, and how to manage them It makes the difference between a stable system and one that breaks down at the slightest provocation.
Furthermore, each distribution has a particular way of handling these privileges. Ubuntu, Debian, Void, openSUSE and other distributions They don't behave exactly the same with the root account, with groups like wheel or with the file sudoersIf you manage servers (VPS, cloud, or dedicated) or simply want to manage your Linux system with ease, you'll want to understand how the root user and the `root` command work. sudo, the use of su and the management of administrative permissions.
What exactly is the root user in Linux?
In Linux and other UNIX-like systems, the user root is the account with UID 0The special identifier that grants full control over the system. This account is usually also associated with the GID 0 (main group) root), which allows you to read, modify or delete any file, manage processes, change permissions and touch any section of the file system, without restrictions.
When we talk about “being root”, we are referring to log in or get a shell which runs with UID 0. It's not simply "having more permissions": it's using the account that has absolute power over the systemEverything you do under that identity is executed without barriers.
That's a different matter. have root privilegesThis means that your regular user (for example, with UID 1000) can, through tools such as sudoThis allows you to execute certain commands "as if you were root," without your session identity permanently changing. In practice, you can perform the same administrative tasks, but within more controlled timeframes and with better traceability.
Difference between being root and having root privileges
It is important to clearly separate the concepts, because Logging in as root is not the same as running something with root privileges.This is where both the UID 0 account and privilege escalation mechanisms (sudo, su, groups like wheel, etc.) come into play.
When You are the root user (UID 0, GID 0) and you do a idYou'll see something like this:
uid=0(root) gid=0(root) groups=0(root)
This indicates that the current session belongs to root and that everything you execute will have those permissions. There's no need to type anything. sudo in front of nothing: any command has free reinThat's why it's so dangerous to stay in a root shell for too long.
However, when you use sudoNormally, you'll still be your "normal" user (for example, UID 1000), but the command will temporarily run as UID 0. If you do:
sudo apt update
Your session remains that of your user, but only that specific command It runs with administrator privileges. The same applies if you launch:
sudo systemctl restart apache2
In both cases, the identity shown in the authentication logs indicates which user has used sudo, which contributes traceability and individual responsibility.
The case of Wheel, Sudoers and management groups
In some distributions (such as Void Linux, or many BSD derivatives) there is a group wheel, which is used for control who can use sudoIn others (such as Ubuntu and Debian in their typical configuration) the group is used sudo to grant that ability. Each distro organizes it in its own way, but the idea is the same: only users who belong to certain groups can escalate privileges.
If Void Linux tells you to add your user to wheelThe normal thing to do would be to run something like:
sudo usermod -aG wheel tu_usuario
Then, when doing idYou should see the wheel group listed among the subgroups. If it doesn't appear, it may be that The change will not be applied until you log outor that the system manages access in a somewhat different way (for example, by relying on PAM or a specific configuration of sudo o su that does not require including a wheel in all cases).
In systems like Ubuntu or Debian, the key group is usually sudoTo add a user:
sudo adduser nombre_de_usuario sudo
The finest level of control is achieved by editing the file / Etc / sudoers (or files in /etc/sudoers.d/) always using visudo, so that you can define which exact commands each user or group can execute. with root privileges, instead of giving a total free rein.
Root in Ubuntu: security policy and use of sudo
Ubuntu follows a fairly clear philosophy: The root account exists, but it's not used to log in directly.Upon system installation, root has UID 0, as in any UNIX system, but is not assigned a usable password for logging in. Instead, intensive use of sudo.
This means that, by default, You cannot enter the TTY or the graphical interface as root with a passwordbecause there is no password configured for that user. This decision reduces the attack surface against brute-force attempts and prevents people from unnecessarily spending all day working as root.
The "normal" flow in Ubuntu is: you log in with your user, that user belongs to the group sudoAnd when you need to do some administration, you run the command with sudo and you write your own passwordnot the root account. This way, the system records who did what, when, and with what command.
If at any point you want a full shell as root (for example, to perform a series of tasks in succession), you can use:
sudo -i
sudo su -
Both will give you one interactive root shellThis usually loads the user's login environment. To exit this mode, simply run exit or press Ctrl + D.
Is the root user always available?
The distribution doesn't matter: The root account always exists internally because it's the one with UID 0. What changes depending on the distro is whether or not that account has a valid password, whether or not direct login is allowed, and under what conditions it can be used.
In the case of openSUSE (for example, Tumbleweed), during installation you can technically leave the root password blank or configure the system so that the normal user has administrative privileges using sudoThat can cause not sure if root is “active” Or not. But the root account itself is always there; it's just that... you cannot authenticate with it because a password has not been set or because the system blocks it using PAM or login policies.
when you use su To switch to root and enter your user password instead of the root password, normally you will not workunless the distro has it configured su to accept the sudoer user's password instead of root's (less common). Most commonly, su It will ask for the password of the target user, that is, the root password if you do a simple su.
Furthermore, if you notice that when doing su To become root, your shell continues reading functions or aliases from your normal user; you may be using a variant like su without a hyphen (su against su -), which makes it The root login environment does not fully loadThat's why you can continue using your .bashrc or your zsh configuration, generating errors in functions that do not exist for the root account.
Remote access as root via SSH
In many servers, when you hire a VPS or a dedicated server, the provider gives you SSH access directly as rootwith a password or, even better, with an SSH key. From a Linux system, the connection is as simple as:
ssh root@IP-del-servidor
In Windows, it is common to use a client such as PuTTYYou simply need to enter the server's IP address in the field. Host Name, click on Open and, when the terminal window appears, Log in as root with the provided password or with the configured key.
You can also connect with any other user on the server, and once inside, escalate to root with sudo or su if that user belongs to the appropriate groups or has the corresponding configuration in /etc/sudoersIn that case, you work with limited permissions until you need to perform a specific administrative task.
Risks of using root carelessly
Root privileges are incredibly useful, but also a double-edged sword. Any typographical errors or misunderstood commands This can result in total data loss, system instability, or security holes that leave your machine vulnerable.
One of the clearest dangers is accidentally deleting or modifying system filesAs root, there is no "Are you sure?" or recycle bin. A command like:
sudo rm -rf /
or a misspelled variant (with the wrong path, an extra space, a misplaced wildcard…) may Delete half of the file system without asking for confirmationAnd recovery, if it is possible at all, is usually complicated and very partial.
There is also the issue of execution scripts downloaded from the Internet with root permissionsIf a script is malicious or poorly programmed, it can delete sensitive files, change critical settings, install malware, disable defenses, or add backdoors without your knowledge. And if you launched it with sudoYou have given him unlimited permissions.
In multi-server environments (production, testing, development), working as root on multiple terminals simultaneously increases the risk of execute a command on the wrong machineA simple restart or deletion performed in production by mistake can take a service offline and cause a major problem.
To make matters worse, when you get used to always working as root, it's easy to get too relaxed and not to double-check what you writeReducing the time you spend with elevated privileges and carefully reviewing commands before pressing Enter is crucial to avoid messing things up.
Root and security: attacks, logs, and auditing
From a security standpoint, root is a single point of failureIf an attacker gains root privileges (either by stealing credentials, exploiting a vulnerability, or tricking you into running something malicious), they gain complete control over the machine.
On servers exposed to the Internet, enabling direct root access via SSH using only a password is opening the door to continuous brute-force attacksAutomated bots attempt to log in as root Constantly testing password combinations. If the password is weak or reused on other services, you're done for.
Furthermore, if you always work as root, any vulnerable application running under that identity (a browser, a misconfigured web server, etc.) can serve as an entry point. As soon as that application is compromised, the attacker inherits all permissions.
Another major problem is the lack of traceabilityWhen using sudo, administrative actions are logged in /var/log/auth.log or in the journal (journalctl): which user launched which command and when. If, on the other hand, everyone logs in directly as root, the logs only indicate "root did this", without being able to determine who was actually behind it.
In environments where security standards are required (ISO 27001, PCI DSS and similar), that traceability and individual responsibility is key. Always working as root without using sudo makes audits more difficult.This complicates problem-solving and often goes against the best practices required by many compliance frameworks. Furthermore, the use of secure hardware such as dev-tpm0 and TPM It can strengthen the integrity and auditability of the system.
Ways to obtain root privileges
In practice, most modern distributions use three main mechanisms to access administrator privileges: sudo, su and direct login (local or remote). Each has its own context and risks.
To execute a single command with root privileges, the most common way is to use:
sudo comando argumentos
For example:
sudo apt update
sudo apt install firefox
sudo systemctl restart apache2
sudo nano /etc/ssh/sshd_config
With this, You don't permanently change usersOnly that command runs with UID 0, and it records who launched it. For most daily administrative tasks, this is the safest option.
If you need a more persistent root session because you're going to run several commands in a row, you can use:
sudo -i
sudo su -
These commands give you a root shell, typically loading the root login environment (variables, PATH, etc.). This is very convenient for certain lengthy tasks, but It's best to abandon that mode as soon as you finish. with exitThe less time you spend as root, the less chance there is of making a mistake.
Enable and manage the root password
In Ubuntu and other distros, although it is discouraged, you can assign a password to the root account to allow it to be used directly. The typical command is:
sudo passwd root
The system will first ask for your user password (to validate the use of sudo) and then it will ask you twice for the new password you want to assign to root. From that moment on, root will have a defined password And, if authentication policies allow it, you could log in locally or use su by entering that key. On devices like Raspberry Pi, for example, it's advisable change default password.
If at any time you want block root login Without deleting the account, you can:
sudo passwd -l root
This disables the password (without completely removing it), preventing direct access. To revert this:
sudo passwd -u root
In any case, especially with Ubuntu, the general recommendation is Do not use root with a password for everyday useIt's much more sensible to continue working with your normal user account and use sudo when necessary.
SSH configuration to allow or deny root
For security reasons, many server installations include root login via SSH disabledTo change this behavior (although it's not ideal), you need to edit the OpenSSH configuration file: /etc/ssh/sshd_config.
The typical procedure is:
- Make sure root has a password If you plan to use that authentication method:
sudo passwd root. - Edit SSH settings with root privileges:
sudo nano /etc/ssh/sshd_config - Locate (or add) the directive
PermitRootLoginand set it toyesif you want to allow direct root access with a password. - Restart the SSH service to apply the changes:
sudo systemctl restart ssh(osshd(depending on the distribution).
The most sensible thing to do, if you need some flexibility without opening the door too wide, is to use PermitRootLogin prohibit-password so that only those who accept key authentication and not by password. Even so, the preferred option is usually to log in as a normal user and then use sudo.
If you want to strengthen security, simply reverse these steps: in sshd_config you put PermitRootLogin no, restart the service and, if you want, lock the root account with sudo passwd -l rootThis forces them to All remote administration must be done through specific users with sudo privileges.As a complementary measure, consider using dm-verity on Linux to protect the integrity of the system.
Edit sudoers and grant root permissions to other users
There are times when you need a newly created user to be able to run commands as rootFor example, imagine you have created a user testftp with useradd o adduserBut when you try to use sudo You will see the following message: testftp is not in the sudoers file.
The "quick" way in many Debian/Ubuntu-based distributions is to add the user to the group sudo:
sudo adduser testftp sudo
In other environments, or if you want finer control, you can edit the file. /etc/sudoers (or add a specific file in /etc/sudoers.d/) always using:
sudo visudo
Inside, you can add a line copying the root template but for that user:
testftp ALL=(ALL:ALL) ALL
With this, testftp will be able to execute any command as root. Using sudo, just like root (but with traceability). If you need stricter restrictions, you can limit allowed commands, require TTY, force password entry, etc.
On more sensitive servers, it is common practice not to grant "full powers" to any user in the sudo group, but rather to define in sudoers exactly what can and cannot be doneFor example, allowing the management of only a specific service or certain administrative scripts.
Once edited and saved with visudoThe affected user should no longer see the "not in the sudoers file" error and will be able to escalate privileges in a controlled manner.
Best practices when using root and sudo
Working with root privileges is not just about knowing which commands to use, but also adopt sensible safety habitsSome basic recommendations worth internalizing:
First, try Use sudo only for specific commands Whenever possible. The less time you spend in a root shell, the less chance there is of making a serious mistake. A short series of commands with `sudo` is usually safer than opening a root session and forgetting to log out.
If you need to use sudo -i o sudo su -Do it when you are sure that you are going to run a group of administrative tasks one after the other. As soon as you're done, exit root. with exitLeaving a root session open in the background, especially on a shared machine or an accessible desktop, greatly increases the risk.
Never open a browser, email client, or suspicious documents from a root session. Any exploits affecting these applications could be dangerous. It will inherit the permissions of the account that executes them.Whenever you interact with untrusted content, do so as a normal user.
Another key point is Do not run unknown scripts with sudo without reading them first. If someone tells you to "paste this curl | sh with sudo" and you do it without looking, you're giving them the keys to your system. Open the script in a text editor, check what it does, where it comes from, and if you don't understand it or don't trust it, don't run it.
Whenever possible, download software and scripts from official or highly reputable sourcesVerify checksums when available and, if in doubt, test first in a virtual machine or container that you can discard if something goes wrong.
Finally, take advantage of the archive /etc/sudoers to apply the principle of least privilegeIt gives each user only the permissions they need, no more, and logs all actions with sudo so you can review what each person has done in case of a problem.
Understanding what the root user is, how root privileges differ from those of the UID 0 account, and using tools like sudo, su, admin groups and SSH configurationIt is possible to manage any Linux system with much more security and peace of mind, avoiding unnecessary scares and always knowing who did what and with what permissions.
