Advanced password manipulation in sudo

Special Privileges

Article from Issue 170/2015
Author(s):

Sudo provides the building blocks to secure your system exactly the way you want it.

If you know sudo, you probably know it from Ubuntu, in which you enter your password in return for temporary root privileges. However, Ubuntu's setup is only one of many for sudo. By editing /etc/sudoers, you can configure sudo's password requirements and other features to secure your system in exactly the way you prefer.

Sudo exists for the purposes of minimizing your exposure when you are root user. Because the root account gives full access to your files, your system is at its most vulnerable when you are root. Consequently, you want to minimize your time as root and perhaps even make the root password hard to find.

The sudoers file takes a lot of options, and a careless choice could lock you out of the root account altogether. To avoid this possibility, always edit /etc/sudoers with the visudo command. Visudo creates a temporary copy of sudoers to edit, then checks it for errors. If any errors are found, visudo gives their approximate location by line and gives you three options: to re-open the editor to correct the errors (e); to exit, discarding your edits (X); or to quit (Q) and save the temporary file to the permanent sudoers file. This last option is something that you obviously should not do unless you are very confident that you know better than visudo, because you could prevent sudoers from working at all. Some compilations of visudo, such as Ubuntu's, list the possible choices, whereas others, such as openSUSE's, do not.

[...]

Use Express-Checkout link below to read the full article (PDF).

Buy this article as PDF

Express-Checkout as PDF
Price $2.95
(incl. VAT)

Buy Linux Magazine

SINGLE ISSUES
 
SUBSCRIPTIONS
 
TABLET & SMARTPHONE APPS
Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • Sudo Voodoo

    By taking the time to learn sudo's many options, you can make your system more secure.

  • Strict Education

    "I've seen penguins that can type better than that." If you give sudo the wrong password, you deserve to be shouted at, says sys admin columnist Charly. He is not exempt from the insult and sees it as an opportunity to raise sudoing awareness.

  • Sudo and PolicyKit

    If you give users who are usually supervised more scope to help themselves, they will need additional privileges. The sudo tool and the PolicyKit authorization service can control who does what on Linux.

  • Privilege Escalation

    Even a small configuration error or oversight can create an opening for privilege escalation. These real-world escalation techniques will help you understand what to watch for.

  • PHP for Sysadmins

    Most admins tend to use the shell, Perl,or Python if they need a system administration script. But there is no need for web programmers to learn another language just to script a routine task. PHP gives admins the power to program command-line tools and even complete web interfaces.

comments powered by Disqus
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters

Support Our Work

Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.

Learn More

News