How To: Lock Out A User Account

This will probably be a short article and one that’s not all that complicated as we discuss how to lock out a user account. Unless you’re a fairly advanced home user, this probably won’t be of much interest to you. If you’re looking to advance your career and work in IT, this will be more valuable to you.

I’ve somehow covered creating a new user twice. I’ll link to one article:

How To: Create A New User

That’s the most recent version. The first one was a couple of years prior, so you can see why there’d be a duplicate. That’s a long time and that’s a whole lot of articles between the two. It happens.

Let’s say you’re firing Peter because Peter has been drinking on the job. You’d work in tandem with human resources and security. What you’d do is you’d wait for Peter to be called into HR and then you’d lock out Peter’s account. You wouldn’t delete it yet, you’d just prevent him from logging in. After that and Peter’s official firing, security would escort him out of the building.

Then again, you could have a shared server with someone. That someone might be acting fishy and you might want to take time to check on their account. That’s when you lock out a user account. You lock out the account (killing any processes owned by them) and do your investigation. 

In short, there are a bunch of excellent reasons why you’d want to lock out a user account. Knowing how to do so is just good security. Knowing when to do so is just good administration. So, let’s learn to do so…

The passwd Command:

The tool we’ll be using is one that you certainly have installed by default. You won’t need to install anything fancy. Your version of Linux will come with the appropriate account management tools.

That tool? That tool is the passwd command. You can verify that passwd is properly installed with the following command:

which passwd

The output should probably match this:

$ which passwd
/usr/bin/passwd

If you check the man page (with man passwd) you’ll see that there are plenty of options but it’s nothing too complicated. Assuming you’ve generated a spare user account, you can play around with the various commands in a mostly harmless way. Mostly…

We’re interested in the -l flag. You can also just use the –lock flag if you prefer to spell it out. Both flags will perform the same. I suppose you can use the longer flag if you’re sharing the command with other people. That way they’ll have an idea of what the command is doing.

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Lock Out A User Account:

You will need an open terminal, of course. If you’re in a position where you’re going to lock out a user account, you probably already know how to access the terminal. If not, most of you can just press CTRL + ALT + T to open up your terminal.

To lock out a user account, the syntax is simple:

sudo passwd -l <username>

Or, as mentioned above, you can use -lock instead:

sudo passwd --lock <username>

For example, you can lock that Peter dude out easily:

sudo passwd -l peter

If it turns out that Peter wasn’t to blame, or your co-admin wasn’t doing anything fishy, you can easily undo this. This is one of the reasons why you don’t delete the account immediately. If you lock the account, you can undo it. If you delete the account, it’s a whole lot of work to recreate it beyond just basic account creation.

To do that whole unlock a user account, the syntax is pretty much the same. This time around, we’re using the -u flag. Of course, you can use the –unlock flag if you prefer.

Again, the syntax is simple:

sudo passwd -u <username>

Or, if you prefer to spell it out:

sudo passwd --unlock <username>

Using the aforementioned Peter above, an example would look like this:

sudo passwd -u peter

I’m sure you know that all user accounts must be in lowercase letters. It follows that these commands are also case-sensitive. Linux is like that. Case matters a great deal in Linux. Unless you’ve set up some sort of alias, CD is not the same as cd. So, remember that in your Linux travels!

Closure:

If you ever need to know how to lock out a user account, you can refer to this article. You should be able to easily find it using the search function here on the site. It seemed like a good topic to write about and a good time to test the sponsorship features.

That’s right. The astute among you will have noticed some sponsorship. Those same astute people may have noticed that you’re not seeing any other ads. Funding the site is not essential, but it is nice. We’ve got to pay the bills one way or another. Right now, I shoulder most of those bills. ‘Snot like folks donate consistently (or often, for that matter). So, we’ll try this sponsorship for a while and see how things go. If you don’t like sponsored content, you can just skip that section of the page.

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