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Configure and run sudo on FreeBSD


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In this tutorial, we’ll introduce a utility called sudo, which is a program that enables a system administrator to grant limited root access to non-admin users. Sudo is different from su because it uses the passwords assigned to sudo users for identification and log in and not that of the target users, which is the exact opposite of what su does. It also allows for a limited transfer of admin privileges to users and user groups selected by the admin. These privileges include but aren’t limited to root executability of a selected handful of commands while keeping a detailed log for each. This way, an admin can pass on the privileges to different users, and all user keep their credentials hidden from other users.

Follow the instructions in this guide to set up and use the sudo command on FreeBSD 9.x/10.x/11.x/12.x system.

Tutorial Overview- Install sudo on FreeBSD

Here’s an overview on how to go about installing sudo on a FreeBSD system:

  • First, you’d open the terminal and log into the remote server
  • Then use the following ssh commands to update your package database:
$ pkg update && pkg upgrade

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Then we’d install sudo with the following command:

$ pkg install sudo

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Lastly, you’ll see how to make configurations to sudo access to match the FreeBSD architecture and your operational requirements.

Part 1: Installing sudo on FreeBSD

The following are detailed explanations on step 3 to install sudo on FreeBSD. We’ll present two different methods you may choose from to your liking.

With FreeBSD port system`

We can use the FreeBSD port system to install sudo. Run the command below to install the port:

$ cd /usr/ports/security/sudo/ && make install clean

Using pkg command

Get the latest FreeBSD updated version of sudo (like FreeBSD 12.x+) by typing in:

$ pkg install sudo

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Part 2: Configuring Sudo on FreeBSD

To configure sudo, we’ll need to edit the default configuration file. Head over to /usr/local/etc/sudoers to access the file. This file should not be tempered without the visudo command, as not using the visudo command can lead to denial of access as well as critical syntax errors under which sudo refuses to perform.

So make sure to use the command below before you edit anything within the file:

$ su -
$ visudo

To grant admin privileges to a user, you’d use the command syntax below:

# younis ALL=(ALL) ALL

Similarly, you can delegate the commands to a group of users with:

# %wheel ALL=(ALL) ALL

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Remember to save the changes before you exit the file.

Part 3: Using Sudo on FreeBSD

Let’s have an overview of some of the basic things you can do with sudo:

Creating a root user

The command below lets you run the shell as a target user.

$ sudo -s

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Type the following to run the login shell

$ sudo -i

Finally, the id command lets you authenticate user credentials:

$ id

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Execute commands as root

Type in the command below, replacing the indicators with relevant variables:

$ sudo /path/to/command
$ sudo /path/to/command arg1

To demonstrate, we’ll reboot the ftpd service:

$ sudo /etc/rc.d/ftpd onerestart

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Check user’s privileges

The following command lists the commands you’re allowed to execute as a root user:

$ sudo -l

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Wrapping up

This tutorial demonstrated the installation of Sudo on FreeBSD 9.x/10.x/11.x/12.x system. We listed the two ways to install Sudo: with the FreeBSD system port and by adding the binary package file to FreeBSD.

You’ve also learned how to edit the default config file to configure Sudo on FreeBSD. It is located /usr/local/etc/sudoers. You also saw how to create a new root user and how to run commands with sudo privileges.

Getting used to working with sudo is easy, although it takes some time. Hopefully, this tutorial was enough to have you get started with sudo.

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