August 14, 2019

How to Create a Restricted User to Connect to MySQL / PostgreSQL Remotely via GUI Client without SSH Access

Sometimes we need to add a user to a pretty locked down server just for them to login to MySQL / PostgreSQL via their GUI client without giving them any other access. It's actually pretty easy to do so in Ubuntu.

Let's get started with these 5 simple steps.

1. Create our new User

Let's call him dbuser. Then gives him a password via passwd.

sudo useradd -s /usr/sbin/nologin dbuser
sudo passwd dbuser2

Basically what /usr/sbin/nologin does is to create a shell that has no login access. That way when dbuser tries to SSH into the server, his shell access would be closed immediately preventing him from tinkering around in the server.

While this stops the user from accessing SSH, it does not block the user from tunnelling through SSH and accessing the databases as you will see.

2. Update our SSH Configurations

If you follow the best practises around for SSH, you would probably have disabled password authentication for your server. That's good.

Here, we want to enable password authentication specifically for dbuser so that it's easier for a non-technical user to login via his favourite database GUI. So let's do that.

sudo nano /etc/ssh/sshd_config

Go to the end of the file (very important to be the end of the file) and add the following lines:

Match user dbuser
    PasswordAuthentication yes

With these 2 lines, we have enabled PasswordAuthentication specifically for dbuser only and not anyone else.

Now restart the SSH service for the new settings to take effect.

service ssh reload

3. Logging in with GUI

Now setup your respective GUI tool to connect to MySQL / PostgreSQL via SSH, it should work.

Here's a sample screenshot from TablePlus. Sample Settings for TablePlus

Sample Settings for TablePlus

4. Testing with SSH

While it worked for the GUI client, we still need to make sure that dbuser has no SSH access. Let's SSH into our server with dbuser and you should see similar output as the following:

SSH Login for dbuser

Just as expected, dbuser wasn't able to log into the server.

However, the server seems to be showing a lot of unnecessary info to the user. Personally I don't like those information to be exposed, so let's hide them away.

Note: Your server may not show these informations and that's fine. You can skip step 5 if you are happy with the messages being displayed when dbuser logs in.

5. Update Message of the Day

What we see in step 4 is called MOTD, or Message of the Day.

To hide away the information is really simple. All we need is to create a .hushlogin file in user's home folder:

mkdir /home/dbuser
touch /home/dbuser/.hushlogin

Now when you try to login, you should see a much simplified output like this:

SSH Login for dbuser

Much better!


And now you have a happy user who can log into MySQL / PostgreSQL without the risk of disrupting the server.