How To Configure Remote Access for MongoDB on Ubuntu 18.04

An earlier version of this tutorial was written by Melissa Anderson.

Introduction

MongoDB, also known as Mongo, is an open-source document database used commonly in modern web applications. By default, it only allows connections that originate on the same server where it’s installed. If you want to manage MongoDB remotely or connect it to a separate application server, there are a few changes you’d need to make to the default configuration.

In this tutorial, you will configure a MongoDB installation to securely allow access from a trusted remote computer. To do this, you’ll update your firewall rules to provide the remote machine access to the port on which MongoDB is listening for connections and then update its configuration file to change its IP binding setting. Then, as a final step, you’ll test that your remote machine is able to make the connection to your database successfully.

Prerequisites

To complete this tutorial, you’ll need:

• A server running Ubuntu 18.04. This server should have a non-root administrative user and a firewall configured with UFW. Set this up by following our initial server setup guide for Ubuntu 18.04.
• MongoDB installed on your server. This tutorial assumes that you have MongoDB 4.4 or newer installed. You can install this version by following our tutorial on How To Install MongoDB on Ubuntu 18.04.
• A second computer from which you’ll access your MongoDB instance. For simplicity, this tutorial assumes that this machine is another Ubuntu 18.04 server, with a non-root administrative user and a UFW firewall configured following our initial server setup guide for Ubuntu 18.04. However, Steps 1 and 2, which describe the actual procedure for enabling remote connectivity on the database server, will work regardless of what operating system the remote machine is running.

Lastly, while it isn’t required to complete this tutorial, we strongly recommend that you secure your MongoDB installation by creating an administrative user account for the database and enabling authentication. To do this, follow our tutorial on How To Secure MongoDB on Ubuntu 18.04.

Step 1 — Adjusting the Firewall

Assuming you followed the prerequisite initial server setup tutorial and enabled a UFW firewall on your server, your MongoDB installation will be inaccessible from the internet. If you intend to use MongoDB only locally with applications running on the same server, this is the recommended and secure setting. However, if you would like to be able to connect to your MongoDB server from a remote location, you have to allow incoming connections to the port where the database is listening by adding a new UFW rule.

Start by checking which port your MongoDB installation is listening on with the lsof command. This command typically returns a list with every open file in a system, but when combined with the -i option, it lists only network-related files or data streams.

The following command will redirect the output produced by lsof -i to a grep command that searches for a string named mongo:

sudo lsof -i | grep mongo

This example output shows that the mongod process is listening for connections on its default port, 27017:

Output
. . .
mongod    82221         mongodb   11u  IPv4 913411      0t0  TCP localhost:27017 (LISTEN)
. . .

In most cases, MongoDB should only be accessed from certain trusted locations, such as another server hosting an application. One way to configure this is to run the following command on your MongoDB server, which opens up access on MongoDB’s default port while explicitly only allowing the IP address of the other trusted server.

Run the following command, making sure to change trusted_server_ip to the IP address of the trusted remote machine you’ll use to access your MongoDB instance:

sudo ufw allow from trusted_server_ip to any port 27017  

In the future, if you ever want to access MongoDB from another machine, run this command again with the new machine’s IP address in place of trusted_server_ip.

You can verify the change in firewall settings with ufw:

sudo ufw status

The output will show that traffic to port 27017 from the remote server is now allowed:

Output
Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere
27017                      ALLOW       trusted_server_ip
OpenSSH (v6)               ALLOW       Anywhere (v6)

You can find more advanced firewall settings for restricting access to services in UFW Essentials: Common Firewall Rules and Commands.

Next, you’ll bind MongoDB to the server’s public IP address so you can access it from your remote machine.

Step 2 — Configuring a Public bindIP

At this point, even though the port is open, MongoDB is currently bound to 127.0.0.1, the local loopback network interface. This means that MongoDB is only able to accept connections that originate on the server where it’s installed.

To allow remote connections, you must edit the MongoDB configuration file — /etc/mongod.conf — to additionally bind MongoDB to your server’s publicly-routable IP address. This way, your MongoDB installation will be able to listen to connections made to your MongoDB server from remote machines.

Open the MongoDB configuration file in your preferred text editor. The following example uses nano:

sudo nano /etc/mongod.conf

Find the network interfaces section, then the bindIp value:

. . .
# network interfaces
net:
  port: 27017
  bindIp: 127.0.0.1

. . .

Append a comma to this line followed by your MongoDB server’s public IP address:

. . .
# network interfaces
net:
  port: 27017
  bindIp: 127.0.0.1,mongodb_server_ip

. . .

Save and close the file. If you used nano, do so by pressing CTRL + X, Y, then ENTER.

Then, restart MongoDB to put this change into effect:

sudo systemctl restart mongod

Following that, your MongoDB installation will be able to accept remote connections from whatever machines you’ve allowed to access port 27017. As a final step, you can test whether the trusted remote server you allowed through the firewall in Step 1 can reach the MongoDB instance running on your server.

Step 3 — Testing Remote Connectivity

Now that you configured your MongoDB installation to listen for connections that originate on its publicly-routable IP address and granted your remote machine access through your server’s firewall to Mongo’s default port, you can test that the remote machine is able to connect.

One way to test that your trusted remote server is able to connect to the MongoDB instance is to use the nc command. nc, short for netcat, is a utility used to establish network connections with TCP or UDP. It’s useful for testing in cases like this because it allows you to specify both an IP address and a port number.

First, log into your trusted server using SSH:

ssh sammy@trusted_server_ip

Then run the following nc command, which includes the -z option. This limits nc to only scan for a listening daemon on the target server without sending it any data. Recall from the prerequisite installation tutorial that MongoDB is running as a service daemon, making this option useful for testing connectivity. It also includes the v option which increases the command’s verbosity, causing netcat to return some output which it otherwise wouldn’t.

Run the following nc command from your trusted remote server, making sure to replace mongodb_server_ip with the IP address of the server on which you installed MongoDB:

nc -zv mongodb_server_ip 27017

If the trusted server can access the MongoDB daemon, its output will indicate that the connection was successful:

Output
Connection to mongodb_server_ip 27017 port [tcp/*] succeeded!

Assuming you have a compatible version of the mongo shell installed on your remote server, you can at this point connect directly to the MongoDB instance installed on the host server.

One way to connect is with a connection string URI, like this:

mongo "mongodb://mongo_server_ip:27017"

mongo "mongodb://username@mongo_server_ip:27017"

With that, you’ve confirmed that your MongoDB server can accept connections from the trusted server.

Conclusion

You can now access your MongoDB installation from a remote server. At this point, you can manage your Mongo database remotely from the trusted server. Alternatively, you could configure an application to run on the trusted server and use the database remotely.

If you haven’t configured an administrative user and enabled authentication, anyone who has access to your remote server can also access your MongoDB installation. If you haven’t already done so, we strongly recommend that you follow our guide on How To Secure MongoDB on Ubuntu 18.04 to add an administrative user and lock things down further.