How To Configure Secure Updates and Installations in WordPress on Ubuntu

Published on November 19, 2013
How To Configure Secure Updates and Installations in WordPress on Ubuntu

Status: Deprecated

This article covers a version of Ubuntu that is no longer supported. If you are currently operate a server running Ubuntu 12.04, we highly recommend upgrading or migrating to a supported version of Ubuntu:

Reason: Ubuntu 12.04 reached end of life (EOL) on April 28, 2017 and no longer receives security patches or updates. This guide is no longer maintained.

See Instead: This guide might still be useful as a reference, but may not work on other Ubuntu releases. If available, we strongly recommend using a guide written for the version of Ubuntu you are using. You can use the search functionality at the top of the page to find a more recent version.


WordPress is the most popular CMS (content management system) used on the internet today. While many people use it because it is powerful and simple, sometimes people make a trade-off for convenience at the expense of security.

This is the case in how you choose to assign directory ownership and permissions, and how you choose to perform upgrades. There are a variety of different methods to do this. We will choose what we consider a relatively secure way of upgrading and installing themes and plugins.

In this guide, we assume that you have gone through your initial server setup. You will also need to install a LAMP stack on your VPS.

We will also assume that you have installed WordPress on Ubuntu 12.04. You can follow our guide on how to install WordPress on Ubuntu 12.04 here.

Once you have the user and required software, you can start following this guide.

Set Up Secure Updates with SSH

If you do not have key-based updates and installations configured, you will get a prompt for connection information whenever you attempt to do either of these tasks.

It will ask you to provide FTP credentials, such as a hostname, FTP username, and FTP password:

WordPress ftp credentials

FTP is an inherently insecure protocol, so we do not recommend you using it in most cases. We will be configuring our installation to use a secure alternative.

Changing Permissions

If you followed the guide on installing WordPress above, you will notice that you gave permission of the web directory to the Apache web user. This is a very quick way to get started, but can potentially be a security risk. In an ideal situation, you would separate the content owner from the web process. We will do this as part of our preparation for allowing SSH updates.

We will create a user called wp-user to own our WordPress installation.

sudo adduser wp-user

You will be asked a lot of question, including the password you want to set. We do not want to set a password, so press “ENTER” through all of the prompts, including the repeated password questions.

Next, change to the /var/www/html directory, where our WordPress files are being served.

cd /var/www/html

We will give our new user ownership over everything under this directory, changing it from the www-data Apache web user that we configured during installation.

sudo chown -R wp-user:wp-user /var/www/html

Create SSH Keys for WordPress

We now need to create an SSH key pair for our WordPress user. Log into the WordPress user by issuing the following command:

sudo su - wp-user

We will create a key pair with the ssh-keygen command:

ssh-keygen -t rsa -b 4096

You will be asked where to store your keys and what to call them. Choose /home/wp-user/wp_rsa. You will also be asked to choose a passphrase. Press “ENTER” through the prompt to create a key without password authentication.

Exit out into your normal user account:


We need to do some maintenance to get the permissions secure. We want to give the WordPress user ownership, but set the www-data group as the group owner. We then want to lock down the other access:

sudo chown wp-user:www-data /home/wp-user/wp_rsa*
sudo chmod 0640 /home/wp-user/wp_rsa*

You need to create the ~/.ssh directory and give it appropriate permissions and ownership so that the web process can log in.

sudo mkdir /home/wp-user/.ssh
sudo chown wp-user:wp-user /home/wp-user/.ssh/
sudo chmod 0700 /home/wp-user/.ssh/

Now, we can input the public key into our authorized keys file so that the user can log in using those credentials. Since we do not have this file already, we can simply copy the public key.

sudo cp /home/wp-user/wp_rsa.pub /home/wp-user/.ssh/authorized_keys

Again, we need to adjust the permissions and ownership of these files to ensure that they can be accessed, while remaining secure:

sudo chown wp-user:wp-user /home/wp-user/.ssh/authorized_keys
sudo chmod 0644 /home/wp-user/.ssh/authorized_keys

Since these keys will only be used for logging in from within the WordPress site, which is on the same computer, we can restrict the login to this server:

sudo nano /home/wp-user/.ssh/authorized_keys

At the very beginning of the file, before any of the other text, add the portion in red to restrict the key usage to the local computer:

<pre> <span class=“highlight”>from=“”</span> ssh-rsa… </pre>

Save and close the file.

Adjust WordPress Configuration to Use Keys

Now, we can install the packages necessary for WordPress to authenticate SSH logins:

sudo apt-get update
sudo apt-get install php5-dev libssh2-1-dev libssh2-php

Now that we have the utilities, we can edit the configuration file and set the values that we configured.

sudo nano /var/www/html/wp-config.php

Towards the end of the file, add these lines:


Save and close the file.

Now, we should restart Apache to take advantage of our new update procedures:

sudo service apache2 restart

Test the Results

Now, we can test to see if our configuration is correct. Log into your WordPress site as an administrator by visiting your site in a browser at the following URL:

<pre> <span class=“highlight”>your_domain.com</span>/wp-admin </pre>

We can check that our settings are configured correctly by attempting to install a new theme. Click on “Appearance” and then “Themes”.

WordPress Themes

At the top, click on “Install Themes”:

WordPress install themes

Search for a theme or click on the “Featured” themes. Click “Install” to install the theme on your site. It should successfully log in, download, and install your package using the key files you specified:

WordPress theme success

You can click on “Activate” to switch to the new theme and then click “visit site” to see the results.

Common Issues

There are some issues that you may run into if you’ve configured your SSH keys incorrectly.

One common error that you may see when trying to push a change through the web interface is:

<pre> Public and Private keys incorrect for <span class=“highlight”>user</span> </pre>

This error is frustratingly unspecific. It can be caused for a variety of reasons, some of which are:

  • Improper permissions on the public key, private key, and the directories that contain them.

    The web process needs to be able to read each of these files, so if the web-server group is the owner, then each file needs to have at least 640 permissions.

    On the other hand, the ~.ssh directory only needs to be accessible to the user that will be logging in. This means the wp-user user in our example. The contents of the directory should be similarly owned by this user and not writable by anyone else.

  • Improper file ownership. These same keys need to be owned by the correct parties. Between owner and group-owner, this is often a mixture of the user being logged in and the web process user.

    In our example, the wp-user owns both the private and public keys, while the www-data group is the group-owner. This allows us to associate them with the correct user while allowing the server to read the files.

  • Improper file formatting. If your public or private key has formatting issues, WordPress will reject the key and refuse to use it. The same goes for the ~/.ssh/authorized_keys file.

    The portion that you added to the authorized_keys file, from="" ... should not exist in the public key. Even though SSH will consider it a valid file, WordPress will reject it as invalid before even sending the attempt to the SSH daemon.

Another common error during the process of updating or installing themes and plugins is:

Could not create directory...

This is usually an issue with incorrect web-directory ownership. If you are going to be updating the files with the wp-user account, the upload directories also need to be owned and accessible by this user.

This means that you need to give the files and folders within the /var/www/html directory to the wp-user account. If you followed the instructions above and are still having problems, make sure you passed the -R option to the chown command.

Another thing to check is that the upload directories have write permissions for the WordPress user. Change to the document root:

cd /var/www/html

If we check the permissions of the files in this folder, we should see write permissions for the owner (first column), but not for the second or third columns:

ls -l

total 180
-rw-r--r--  1 wp-user wp-user   177 Nov 18 15:21 index.html
-rw-r--r--  1 wp-user wp-user   418 Sep 24 20:18 index.php
-rw-r--r--  1 wp-user wp-user    20 Nov 18 15:24 info.php
-rw-r--r--  1 wp-user wp-user 19929 Jan 18  2013 license.txt
-rw-r--r--  1 wp-user wp-user  7128 Oct 23 16:08 readme.html
-rw-r--r--  1 wp-user wp-user  4892 Oct  4 10:12 wp-activate.php
drwxr-xr-x  9 wp-user wp-user  4096 Oct 29 16:08 wp-admin/
-rw-r--r--  1 wp-user wp-user   271 Jan  8  2012 wp-blog-header.php
-rw-r--r--  1 wp-user wp-user  4795 Sep  5 21:38 wp-comments-post.php
-rw-r--r--  1 wp-user wp-user  3350 Nov 19 12:23 wp-config.php
-rw-r--r--  1 wp-user wp-user  3177 Nov  1  2010 wp-config-sample.php
drwxr-xr-x  5 wp-user wp-user  4096 Nov 19 12:25 wp-content/
. . .

As you can see, the file permissions that read -rw-r--r-- and the directory permissions that read drwxr-xr-x indicate that the wp-user, who owns the files and directories, has write permissions and others do not.

A similar check within the wp-content directory, which contains themes, plugins, etc, will show us whether these directories are owned by and writeable by the wp-user user.

cd /var/www/html/wp-content
ls -l

total 16
-rw-r--r-- 1 wp-user wp-user   28 Jan  8  2012 index.php
drwxr-xr-x 3 wp-user wp-user 4096 Oct 29 16:08 plugins
drwxr-xr-x 6 wp-user wp-user 4096 Nov 19 13:10 themes
drwxr-xr-x 2 wp-user wp-user 4096 Nov 19 13:10 upgrade

These directories are correctly configured.


While WordPress is convenient and can be configured and managed relatively easily, it does not mean that security should not be a primary concern for your site.

Something as simple as updating your installation, which should be done immediately upon any security release, should be simple. It also should not be a procedure that forces you to use insecure protocols or set insecure directory permissions.

Securing your update procedure and correct directory permissions is one easy task that can prevent a rather large security concern.

<div class=“author”>By Justin Ellingwood</div>

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Finally got this working. Here’s a couple of tips that will hopefully help save some people a bit of time.

My setup: Ubuntu 14.04, nginx and rest of LEMP stack (php,mysql + varnish)

  1. If you followed the tutorials when setting up your server and site, remember that on Ubuntu 14.04 with nginx your root directory will be

/var/www/html instead of /var/www

  1. If you followed the tutorial for the initial server setup and disabled root login, you need to add this new user with this

“sudo nano /etc/ssh/sshd_config” - without the " "

Add the following to that file:

AllowUser wp-user - replace wp-user with the new user you created

  1. Be sure to change your port in the wp-config file if you changed the default port from 22 to something else:

define(‘FTP_HOST’,‘’); - where there is the :22, you should replace the 22 with whatever you changed your ssh port to earlier.

  1. You’ll need to change permissions on your wp-content/uploads folder. Handing them over to the “wp-user” means your admin account won’t be able to upload to the uploads folder (media, etc.,). Use the following line to revert those changes to your primary wordpress admin account:

sudo chown wp-user:www-data /var/www/html/wp-content/uploads -R

Hope that helps some people figure this out. It was kind of a pain, especially if you’re inexperienced in deploying servers. Thanks for the tutorial, and an even bigger thanks to the commenters who figured a lot of this stuff out.

For anyone with the “Public and Private keys incorrect for user” error

Double check your /etc/ssh/sshd_config

If you previously secured your ssh (as recommended in a guide on DO) to only one account you will need to add the wp-user as well. In the below example I have used demo to represent the first allowed account, wp-user is the second.


AllowUsers demo wp-user

As others have mentioned also I had to change group ownership for the uploads folder to www-data

Hope that helps

Great tutorial. I’ve built a brand new WordPress instance on Azure using Ubuntu 14.04 from scratch using the these DigitalOcean tutorials:

How To Install Linux, Apache, MySQL, PHP (LAMP) stack on Ubuntu 14.04


How To Install Wordpress on Ubuntu 14.04

They were very helpful.

Following this tutorial I was able to update WordPress. However, I was not able to upload a template from my desktop.

I got the dreaded, “Could not create directory…” error.

Reading the Discussion about permissions for web folders and @CTala’s comments provided the fix:

sudo adduser wp-user www-data sudo chown -R www-data:www-data /var/www

Hope this comment helps someone else.

If wp-user owns all the files and directories, how can I use sftp with this user? If I login under my account and use sftp to upload files, it says it doesn’t have the correct permissions. If I try to login as wp-user, it asks for a password, which I did not set per above instructions.

For those with difficulty loading the general setting page (connection reset error) after following this guide, installing “SSH SFTP Updater Support” plugin solved my problem. Bypassing the libssh2 requirement using this plugin somehow solves this issue even though I do have libssh2-1-dev and libssh2-php installed. It’s possibly because my user account has a password and the SSH2 extension didn’t like that? I don’t know.

Hi, after securing wordpress with your instructions I was no more able to enter general-option.php page (Settings -> General) nor remove plugins nor themes.

Found the solution on wordpress support site where they found that you cannot have both FTP_PUBKEY and FTP_PRIKEY ate the same time. Removing FTP_PRIKEY from wp-config.php solve my issue.

I suggest to update your instruction on the** wp-config.php** file

/*define('FTP_PRIKEY','/home/wp-user/wp_rsa'); comment or remove this line*/

Hope that helps :)

Thank you for your very good tutorials, Justin.

I followed your tutorials in its order:

  1. Initial Server Setup with Ubuntu 14.04
  2. How To Install Linux, Apache, MySQL, PHP (LAMP) stack on Ubuntu 14.04
  3. How To Install Wordpress on Ubuntu 14.04
  4. How To Configure Secure Updates and Installations in WordPress on Ubuntu

Here are my notes:

1) Using Ubuntu 14.04, users should use /var/www/html instead of /var/www in your tutorial number 4 above.

2) After completion of tutorial number 4 above, Import plugin could not write into upload folder, but this problem was solved after entering this command:

sudo chown -R :www-data /var/www/html/wp-content/uploads

3) If I follow the tutorial named How To Protect SSH with fail2ban on Ubuntu 12.04, apache test fails in the tutorial number 2 above, “Welcome to nginx!” page is displayed instead of Apache “it works” page. Maybe your staff should update fail2ban tutorial.

  1. In your tutorial number 3, Wordpress files are owned by default user (“demo” user) created in the tutorial 1. However in tutorial number 4, this policy changes and wp-user owns such files. Maybe users create wp-user in the tutorial 3 for the simplicity’s sake.

Hi, I followed the tutorial but when I try to update a plugin, it shows me the ftp login screen with all the fields prefilled with the information defined on the php-config.php file.

The nginx logs the following: error.log:

2014/08/21 14:41:28 [error] 20461#0: *249 rewrite or internal redirection cycle while internally redirecting to "/index.html", client:

Any hint?

@dhruba thanks. And don’t forget to restart ssh after editing sshd_config.

I’m using centos. I was wondering if there is a similar tutorial for centos or what are the changes I need to make if I’m using this tutorial for reference.

The wordpress site is up and running but unable to upload plugins.

Thank you

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