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      How to Install and Secure phpMyAdmin with Nginx on a Debian 9 server


      Introduction

      While many users need the functionality of a database system like MySQL, interacting with the system solely from the MySQL command-line client requires familiarity with the SQL language, so it may not be the preferred interface for some.

      phpMyAdmin was created so that users can interact with MySQL through an intuitive web interface, running alongside a PHP development environment. In this guide, we’ll discuss how to install phpMyAdmin on top of an Nginx server, and how to configure the server for increased security.

      Note: There are important security considerations when using software like phpMyAdmin, since it runs on the database server, it deals with database credentials, and it enables a user to easily execute arbitrary SQL queries into your database. Because phpMyAdmin is a widely-deployed PHP application, it is frequently targeted for attack. We will go over some security measures you can take in this tutorial so that you can make informed decisions.

      Prerequisites

      Before you get started with this guide, you’ll need the following available to you:

      Because phpMyAdmin handles authentication using MySQL credentials, it is strongly advisable to install an SSL/TLS certificate to enable encrypted traffic between server and client. If you don’t have an existing domain configured with a valid certificate, you can follow the guide on How to Secure Nginx with Let’s Encrypt on Debian 9.

      Warning: If you don’t have an SSL/TLS certificate installed on the server and you still want to proceed, please consider enforcing access via SSH Tunnels as explained in Step 5 of this guide.

      Once you have met these prerequisites, you can go ahead with the rest of the guide.

      Step 1 — Installing phpMyAdmin

      The first thing we need to do is install phpMyAdmin on the LEMP server. We’re going to use the default Debian repositories to achieve this goal.

      Let’s start by updating the server’s package index with:

      Now you can install phpMyAdmin with:

      • sudo apt install phpmyadmin

      During the installation process, you will be prompted to choose the web server (either Apache or Lighthttp) to configure. Because we are using Nginx as web server, we shouldn't make a choice here. Press tab and then OK to advance to the next step.

      Next, you’ll be prompted whether to use dbconfig-common for configuring the application database. Select Yes. This will set up the internal database and administrative user for phpMyAdmin. You will be asked to define a new password for the phpmyadmin MySQL user. You can also leave it blank and let phpMyAdmin randomly create a password.

      The installation will now finish. For the Nginx web server to find and serve the phpMyAdmin files correctly, we’ll need to create a symbolic link from the installation files to Nginx's document root directory:

      • sudo ln -s /usr/share/phpmyadmin /var/www/html

      Your phpMyAdmin installation is now operational. To access the interface, go to your server's domain name or public IP address followed by /phpmyadmin in your web browser:

      https://server_domain_or_IP/phpmyadmin
      

      phpMyAdmin login screen

      As mentioned before, phpMyAdmin handles authentication using MySQL credentials, which means you should use the same username and password you would normally use to connect to the database via console or via an API. If you need help creating MySQL users, check this guide on How To Manage an SQL Database.

      Note: Logging into phpMyAdmin as the root MySQL user is discouraged because it represents a significant security risk. We'll see how to disable root login in a subsequent step of this guide.

      Your phpMyAdmin installation should be completely functional at this point. However, by installing a web interface, we've exposed our MySQL database server to the outside world. Because of phpMyAdmin's popularity, and the large amounts of data it may provide access to, installations like these are common targets for attacks. In the following sections of this guide, we'll see a few different ways in which we can make our phpMyAdmin installation more secure.

      Step 2 — Changing phpMyAdmin's Default Location

      One of the most basic ways to protect your phpMyAdmin installation is by making it harder to find. Bots will scan for common paths, like /phpmyadmin, /pma, /admin, /mysql and such. Changing the interface's URL from /phpmyadmin to something non-standard will make it much harder for automated scripts to find your phpMyAdmin installation and attempt brute-force attacks.

      With our phpMyAdmin installation, we've created a symbolic link pointing to /usr/share/phpmyadmin, where the actual application files are located. To change phpMyAdmin's interface URL, we will rename this symbolic link.

      First, let's navigate to the Nginx document root directory and list the files it contains to get a better sense of the change we'll make:

      You’ll receive the following output:

      Output

      total 8 -rw-r--r-- 1 root root 612 Apr 8 13:30 index.nginx-debian.html lrwxrwxrwx 1 root root 21 Apr 8 15:36 phpmyadmin -> /usr/share/phpmyadmin

      The output shows that we have a symbolic link called phpmyadmin in this directory. We can change this link name to whatever we'd like. This will in turn change phpMyAdmin's access URL, which can help obscure the endpoint from bots hardcoded to search common endpoint names.

      Choose a name that obscures the purpose of the endpoint. In this guide, we'll name our endpoint /nothingtosee, but you should choose an alternate name. To accomplish this, we'll rename the link:

      • sudo mv phpmyadmin nothingtosee
      • ls -l

      After running the above commands, you’ll receive this output:

      Output

      total 8 -rw-r--r-- 1 root root 612 Apr 8 13:30 index.nginx-debian.html lrwxrwxrwx 1 root root 21 Apr 8 15:36 nothingtosee -> /usr/share/phpmyadmin

      Now, if you go to the old URL, you'll get a 404 error:

      https://server_domain_or_IP/phpmyadmin
      

      phpMyAdmin 404 error

      Your phpMyAdmin interface will now be available at the new URL we just configured:

      https://server_domain_or_IP/nothingtosee
      

      phpMyAdmin login screen

      By obfuscating phpMyAdmin's real location on the server, you're securing its interface against automated scans and manual brute-force attempts.

      Step 3 — Disabling Root Login

      On MySQL as well as within regular Linux systems, the root account is a special administrative account with unrestricted access to the system. In addition to being a privileged account, it's a known login name, which makes it an obvious target for brute-force attacks. To minimize risks, we'll configure phpMyAdmin to deny any login attempts coming from the user root. This way, even if you provide valid credentials for the user root, you'll still get an "access denied" error and won't be allowed to log in.

      Because we chose to use dbconfig-common to configure and store phpMyAdmin settings, the default configuration is currently stored in the database. We'll need to create a new config.inc.php file to define our custom settings.

      Even though the PHP files for phpMyAdmin are located inside /usr/share/phpmyadmin, the application uses configuration files located at /etc/phpmyadmin. We will create a new custom settings file inside /etc/phpmyadmin/conf.d, and name it pma_secure.php:

      • sudo nano /etc/phpmyadmin/conf.d/pma_secure.php

      The following configuration file contains the necessary settings to disable passwordless logins (AllowNoPassword set to false) and root login (AllowRoot set to false):

      /etc/phpmyadmin/conf.d/pma_secure.php

      <?php
      
      # PhpMyAdmin Settings
      # This should be set to a random string of at least 32 chars
      $cfg['blowfish_secret'] = '3!#32@3sa(+=_4?),5XP_:U%%834sdfSdg43yH#{o';
      
      $i=0;
      $i++;
      
      $cfg['Servers'][$i]['auth_type'] = 'cookie';
      $cfg['Servers'][$i]['AllowNoPassword'] = false;
      $cfg['Servers'][$i]['AllowRoot'] = false;
      
      ?>
      

      Save the file when you're done editing by pressing CTRL + X then y to confirm changes and ENTER. The changes will apply automatically. If you reload the login page now and try to log in as root, you will get an Access Denied error:

      access denied

      Root login is now prohibited on your phpMyAdmin installation. This security measure will block brute-force scripts from trying to guess the root database password on your server. Moreover, it will enforce the usage of less-privileged MySQL accounts for accessing phpMyAdmin's web interface, which by itself is an important security practice.

      Step 4 — Creating an Authentication Gateway

      Hiding your phpMyAdmin installation on an unusual location might sidestep some automated bots scanning the network, but it's useless against targeted attacks. To better protect a web application with restricted access, it's generally more effective to stop attackers before they can even reach the application. This way, they'll be unable to use generic exploits and brute-force attacks to guess access credentials.

      In the specific case of phpMyAdmin, it's even more important to keep the login interface locked away. By keeping it open to the world, you're offering a brute-force platform for attackers to guess your database credentials.

      Adding an extra layer of authentication to your phpMyAdmin installation enables you to increase security. Users will be required to pass through an HTTP authentication prompt before ever seeing the phpMyAdmin login screen. Most web servers, including Nginx, provide this capability natively.

      To set this up, we first need to create a password file to store the authentication credentials. Nginx requires that passwords be encrypted using the crypt() function. The OpenSSL suite, which should already be installed on your server, includes this functionality.

      To create an encrypted password, type:

      You will be prompted to enter and confirm the password that you wish to use. The utility will then display an encrypted version of the password that will look something like this:

      Output

      O5az.RSPzd.HE

      Copy this value, as you will need to paste it into the authentication file we'll be creating.

      Now, create an authentication file. We'll call this file pma_pass and place it in the Nginx configuration directory:

      • sudo nano /etc/nginx/pma_pass

      In this file, you’ll specify the username you would like to use, followed by a colon (:), followed by the encrypted version of the password you received from the openssl passwd utility.

      We are going to name our user sammy, but you should choose a different username. The file should look like this:

      /etc/nginx/pma_pass

      sammy:O5az.RSPzd.HE
      

      Save and close the file when you're done.

      Now we're ready to modify the Nginx configuration file. For this guide, we'll use the configuration file located at /etc/nginx/sites-available/example.com. You should use the relevant Nginx configuration file for the web location where phpMyAdmin is currently hosted. Open this file in your text editor to get started:

      • sudo nano /etc/nginx/sites-available/example.com

      Locate the server block, and the location / section within it. We need to create a new location section within this block to match phpMyAdmin's current path on the server. In this guide, phpMyAdmin's location relative to the web root is /nothingtosee:

      /etc/nginx/sites-available/default

      server {
          . . .
      
              location / {
                      try_files $uri $uri/ =404;
              }
      
              location /nothingtosee {
                      # Settings for phpMyAdmin will go here
              }
      
          . . .
      }
      

      Within this block, we'll need to set up two different directives: auth_basic, which defines the message that will be displayed on the authentication prompt, and auth_basic_user_file, pointing to the file we just created. This is how your configuration file should look like when you're finished:

      /etc/nginx/sites-available/default

      server {
          . . .
      
              location /nothingtosee {
                      auth_basic "Admin Login";
                      auth_basic_user_file /etc/nginx/pma_pass;
              }
      
      
          . . .
      }
      

      Save and close the file when you're done. To check if the configuration file is valid, you can run:

      The following output is expected:

      Output

      nginx: the configuration file /etc/nginx/nginx.conf syntax is ok nginx: configuration file /etc/nginx/nginx.conf test is successful

      To activate the new authentication gate, you must reload the web server:

      • sudo systemctl reload nginx

      Now, if you visit the phpMyAdmin URL in your web browser, you should be prompted for the username and password you added to the pma_pass file:

      https://server_domain_or_IP/nothingtosee
      

      Nginx authentication page

      Once you enter your credentials, you'll be taken to the standard phpMyAdmin login page.

      Note: If refreshing the page does not work, you may have to clear your cache or use a different browser session if you've already been using phpMyAdmin.

      In addition to providing an extra layer of security, this gateway will help keep your MySQL logs clean of spammy authentication attempts.

      Step 5 — Setting Up Access via Encrypted Tunnels (Optional)

      For increased security, it is possible to lock down your phpMyAdmin installation to authorized hosts only. You can whitelist authorized hosts in your Nginx configuration file, so that any request coming from an IP address that is not on the list will be denied.

      Even though this feature alone can be enough in some use cases, it's not always the best long-term solution, mainly due to the fact that most people don't access the Internet from static IP addresses. As soon as you get a new IP address from your Internet provider, you'll be unable to get to the phpMyAdmin interface until you update the Nginx configuration file with your new IP address.

      For a more robust long-term solution, you can use IP-based access control to create a setup in which users will only have access to your phpMyAdmin interface if they're accessing from either an authorized IP address or localhost via SSH tunneling. We'll see how to set this up in the sections below.

      Combining IP-based access control with SSH tunneling greatly increases security because it fully blocks access coming from the public internet (except for authorized IPs), in addition to providing a secure channel between user and server through the use of encrypted tunnels.

      Setting Up IP-Based Access Control on Nginx

      On Nginx, IP-based access control can be defined in the corresponding location block of a given site, using the directives allow and deny. For instance, if we want to only allow requests coming from a given host, we should include the following two lines, in this order, inside the relevant location block for the site we would like to protect:

      allow hostname_or_IP;
      deny all;
      

      You can allow as many hosts as you want, you only need to include one allow line for each authorized host/IP inside the respective location block for the site you're protecting. The directives will be evaluated in the same order as they are listed, until a match is found or the request is finally denied due to the deny all directive.

      We'll now configure Nginx to only allow requests coming from localhost or your current IP address. First, you'll need to know the current public IP address your local machine is using to connect to the Internet. There are various ways to obtain this information; for simplicity, we're going to use the service provided by ipinfo.io. You can either open the URL https://ipinfo.io/ip in your browser, or run the following command from your local machine:

      • curl https://ipinfo.io/ip

      You should get a simple IP address as output, like this:

      Output

      203.0.113.111

      That is your current public IP address. We'll configure phpMyAdmin's location block to only allow requests coming from that IP, in addition to localhost. We'll need to edit once again the configuration block for phpMyAdmin inside /etc/nginx/sites-available/example.com.

      Open the Nginx configuration file using your command-line editor of choice:

      • sudo nano /etc/nginx/sites-available/example.com

      Because we already have an access rule within our current configuration, we need to combine it with IP-based access control using the directive satisfy all. This way, we can keep the current HTTP authentication prompt for increased security.

      This is how your phpMyAdmin Nginx configuration should look like after you're done editing:

      /etc/nginx/sites-available/example.com

      server {
          . . .
      
          location /nothingtosee {
              satisfy all; #requires both conditions
      
              allow 203.0.113.111; #allow your IP
              allow 127.0.0.1; #allow localhost via SSH tunnels
              deny all; #deny all other sources
      
              auth_basic "Admin Login";
              auth_basic_user_file /etc/nginx/pma_pass;
          }
      
          . . .
      }
      

      Remember to replace nothingtosee with the actual path where phpMyAdmin can be found, and the highlighted IP address with your current public IP address.

      Save and close the file when you're done. To check if the configuration file is valid, you can run:

      The following output is expected:

      Output

      nginx: the configuration file /etc/nginx/nginx.conf syntax is ok nginx: configuration file /etc/nginx/nginx.conf test is successful

      Now reload the web server so the changes take effect:

      • sudo systemctl reload nginx

      Because your IP address is explicitly listed as an authorized host, your access shouldn't be disturbed. Anyone else trying to access your phpMyAdmin installation will now get a 403 error (Forbidden):

      https://server_domain_or_IP/nothingtosee
      

      403 error

      In the next section, we'll see how to use SSH tunneling to access the web server through local requests. This way, you'll still be able to access phpMyAdmin's interface even when your IP address changes.

      Accessing phpMyAdmin Through an Encrypted Tunnel

      SSH tunneling works as a way of redirecting network traffic through encrypted channels. By running an ssh command similar to what you would use to log into a server, you can create a secure "tunnel" between your local machine and that server. All traffic coming in on a given local port can now be redirected through the encrypted tunnel and use the remote server as a proxy, before reaching out to the internet. It's similar to what happens when you use a VPN (Virtual Private Network), however SSH tunneling is much simpler to set up.

      We'll use SSH tunneling to proxy our requests to the remote web server running phpMyAdmin. By creating a tunnel between your local machine and the server where phpMyAdmin is installed, you can redirect local requests to the remote web server, and what's more important, traffic will be encrypted and requests will reach Nginx as if they're coming from localhost. This way, no matter what IP address you're connecting from, you'll be able to securely access phpMyAdmin's interface.

      Because the traffic between your local machine and the remote web server will be encrypted, this is a safe alternative for situations where you can't have an SSL/TLS certificate installed on the web server running phpMyAdmin.

      From your local machine, run this command whenever you need access to phpMyAdmin:

      • ssh user@server_domain_or_IP -L 8000:localhost:80 -L 8443:localhost:443 -N

      Let's examine each part of the command:

      • user: SSH user to connect to the server where phpMyAdmin is running
      • hostname_or_IP: SSH host where phpMyAdmin is running
      • -L 8000:localhost:80 redirects HTTP traffic on port 8000
      • -L 8443:localhost:443 redirects HTTPS traffic on port 8443
      • -N: do not execute remote commands

      Note: This command will block the terminal until interrupted with a CTRL+C, in which case it will end the SSH connection and stop the packet redirection. If you'd prefer to run this command in background mode, you can use the SSH option -f.

      Now, go to your browser and replace server_domain_or_IP with localhost:PORT, where PORT is either 8000 for HTTP or 8443 for HTTPS:

      http://localhost:8000/nothingtosee
      
      https://localhost:443/nothingtosee
      

      phpMyAdmin login screen

      Note: If you're accessing phpMyAdmin via https, you might get an alert message questioning the security of the SSL certificate. This happens because the domain name you're using (localhost) doesn't match the address registered within the certificate (domain where phpMyAdmin is actually being served). It is safe to proceed.

      All requests on localhost:8000 (HTTP) and localhost:8443 (HTTPS) are now being redirected through a secure tunnel to your remote phpMyAdmin application. Not only have you increased security by disabling public access to your phpMyAdmin, you also protected all traffic between your local computer and the remote server by using an encrypted tunnel to send and receive data.

      If you'd like to enforce the usage of SSH tunneling to anyone who wants access to your phpMyAdmin interface (including you), you can do that by removing any other authorized IPs from the Nginx configuration file, leaving 127.0.0.1 as the only allowed host to access that location. Considering nobody will be able to make direct requests to phpMyAdmin, it is safe to remove HTTP authentication in order to simplify your setup. This is how your configuration file would look like in such a scenario:

      /etc/nginx/sites-available/example.com

      server {
          . . .
      
          location /nothingtosee { 
              allow 127.0.0.1; #allow localhost only
              deny all; #deny all other sources
          }
      
          . . .
      }
      

      Once you reload Nginx's configuration with sudo systemctl reload nginx, your phpMyAdmin installation will be locked down and users will be required to use SSH tunnels in order to access phpMyAdmin's interface via redirected requests.

      Conclusion

      In this tutorial, we saw how to install phpMyAdmin on Ubuntu 18.04 running Nginx as the web server. We also covered advanced methods to secure a phpMyAdmin installation on Ubuntu, such as disabling root login, creating an extra layer of authentication, and using SSH tunneling to access a phpMyAdmin installation via local requests only.

      After completing this tutorial, you should be able to manage your MySQL databases from a reasonably secure web interface. This user interface exposes most of the functionality available via the MySQL command line. You can browse databases and schema, execute queries, and create new data sets and structures.



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      How To Install Go on Debian 9


      Introduction

      Go, also known as golang, is a modern, open-source programming language developed by Google. Increasingly popular for many applications, Go takes a minimalist approach to development, helping you build reliable and efficient software.

      This tutorial will guide you through downloading and installing Go, as well as compiling and executing a basic “Hello, World!” program on a Debian 9 server.

      Prerequisites

      To complete this tutorial, you will need access to a Debian 9 server and a non-root user with sudo privileges, as described in Initial Server Setup with Debian 9.

      Step 1 — Downloading Go

      In this step, we’ll install Go on your server.

      First, install curl so you will be able to grab the latest Go release:

      Next, visit the official Go downloads page and find the URL for the current binary release's tarball. Make sure you copy the link for the latest version that is compatible with a 64-bit architecture.

      From your home directory, use curl to retrieve the tarball:

      • curl -O https://dl.google.com/go/go1.12.5.linux-amd64.tar.gz

      Although the tarball came from a genuine source, it is best practice to verify both the authenticity and integrity of items downloaded from the Internet. This verification method certifies that the file was neither tampered with nor corrupted or damaged during the download process. The sha256sum command produces a unique 256-bit hash:

      • sha256sum go1.12.5.linux-amd64.tar.gz

      Output

      go1.12.5.linux-amd64.tar.gz aea86e3c73495f205929cfebba0d63f1382c8ac59be081b6351681415f4063cf go1.12.5.linux-amd64.tar.gz

      Compare the hash in your output to the checksum value on the Go download page. If they match, then it is safe to conclude that the download is legitimate.

      With Go downloaded and the integrity of the file validated, let's proceed with the installation.

      Step 2 — Installing Go

      We’ll now use tar to extract the tarball. The x flag tells tar to extract, v tells it we want verbose output, including a list of the files being extracted, and f tells it we'll specify a filename:

      • tar xvf go1.12.5.linux-amd64.tar.gz

      You should now have a directory called go in your home directory. Recursively change the owner and group of this directory to root, and move it to /usr/local:

      • sudo chown -R root:root ./go
      • sudo mv go /usr/local

      Note: Although /usr/local/go is the officially-recommended location, some users may prefer or require different paths.

      At this point, using Go would require specifying the full path to its install location in the command line. To make interacting with Go more user-friendly, we will set a few paths.

      Step 2 — Setting Go Paths

      In this step, we'll set some paths in your environment.

      First, set Go's root value, which tells Go where to look for its files:

      At the end of the file, add the following lines:

      export GOPATH=$HOME/work
      export PATH=$PATH:/usr/local/go/bin:$GOPATH/bin
      

      If you chose a different installation location for Go, then you should add the following lines to this file instead of the lines shown above. In this example, we are adding the lines that would be required if you installed Go in your home directory:

      export GOROOT=$HOME/go
      export GOPATH=$HOME/work
      export PATH=$PATH:$GOROOT/bin:$GOPATH/bin
      

      With the appropriate lines pasted into your profile, save and close the file.

      Next, refresh your profile by running:

      With the Go installation in place and the necessary environment paths set, let’s confirm that our setup works by composing a short program.

      Step 3 — Testing Your Installation

      Now that Go is installed and the paths are set for your server, you can ensure that Go is working as expected.

      Create a new directory for your Go workspace, which is where Go will build its files:

      Then, create a directory hierarchy in this folder so that you will be able to create your test file. We’ll use the directory my_project as an example:

      • mkdir -p work/src/my_project/hello

      Next, you can create a traditional "Hello World" Go file:

      • nano ~/work/src/my_project/hello/hello.go

      Inside your editor, add the following code to the file, which uses the main Go packages, imports the formatted IO content component, and sets a new function to print "Hello, World!" when run:

      ~/work/src/my_project/hello/hello.go

      package main
      
      import "fmt"
      
      func main() {
          fmt.Printf("Hello, World!n")
      }
      

      When it runs, this program will print "Hello, World!," indicating that Go programs are compiling correctly.

      Save and close the file, then compile it by invoking the Go command install:

      • go install my_project/hello

      With the program compiled, you can run it by executing the command:

      Go is successfully installed and functional if you see the following output:

      Output

      Hello, World!

      You can see where the compiled hello binary is installed by using the which command:

      Output

      /home/sammy/work/bin/hello

      The “Hello, World!” program established that you have a Go development environment.

      Conclusion

      By downloading and installing the latest Go package and setting its paths, you now have a system to use for Go development. To learn more about working with Go, see our development series How To Code in Go. You can also consult the official documentation on How to Write Go Code.

      Additionally, you can read some Go tips from our development team at DigitalOcean.



      Source link

      How To Use Certbot Standalone Mode to Retrieve Let’s Encrypt SSL Certificates on Debian 9


      Introduction

      Let’s Encrypt is a service offering free SSL certificates through an automated API. The most popular Let’s Encrypt client is EFF’s Certbot.

      Certbot offers a variety of ways to validate your domain, fetch certificates, and automatically configure Apache and Nginx. In this tutorial, we’ll discuss Certbot’s standalone mode and how to use it to secure other types of services, such as a mail server or a message broker like RabbitMQ.

      We won’t discuss the details of SSL configuration, but when you are done you will have a valid certificate that is automatically renewed. Additionally, you will be able to automate reloading your service to pick up the renewed certificate.

      Prerequisites

      Before starting this tutorial, you will need:

      • A Debian 9 server with a non-root, sudo-enabled user and basic firewall set up, as detailed in this Debian 9 server setup tutorial.
      • A domain name pointed at your server, which you can accomplish by following “How to Set Up a Host Name with DigitalOcean.” This tutorial will use example.com throughout.
      • Port 80 or 443 must be unused on your server. If the service you’re trying to secure is on a machine with a web server that occupies both of those ports, you’ll need to use a different mode such as Certbot’s webroot mode or DNS-based challenge mode.

      Step 1 — Installing Certbot

      Debian 9 includes the Certbot client in their default repository, and it should be up-to-date enough for basic use. If you need to do DNS-based challenges or use other newer Certbot features, you should instead install from the stretch-backports repo as instructed by the official Certbot documentation.

      Use apt to install the certbot package:

      You may test your install by asking certbot to output its version number:

      Output

      certbot 0.28.0

      Now that we have Certbot installed, let's run it to get our certificate.

      Step 2 — Running Certbot

      Certbot needs to answer a cryptographic challenge issued by the Let's Encrypt API in order to prove we control our domain. It uses ports 80 (HTTP) or 443 (HTTPS) to accomplish this. Open up the appropriate port in your firewall:

      Substitute 443 above if that's the port you're using. ufw will output confirmation that your rule was added:

      Output

      Rule added Rule added (v6)

      We can now run Certbot to get our certificate. We'll use the --standalone option to tell Certbot to handle the challenge using its own built-in web server. The --preferred-challenges option instructs Certbot to use port 80 or port 443. If you're using port 80, you want --preferred-challenges http. For port 443 it would be --preferred-challenges tls-sni. Finally, the -d flag is used to specify the domain you're requesting a certificate for. You can add multiple -d options to cover multiple domains in one certificate.

      • sudo certbot certonly --standalone --preferred-challenges http -d example.com

      When running the command, you will be prompted to enter an email address and agree to the terms of service. After doing so, you should see a message telling you the process was successful and where your certificates are stored:

      Output

      IMPORTANT NOTES: - Congratulations! Your certificate and chain have been saved at: /etc/letsencrypt/live/example.com/fullchain.pem Your key file has been saved at: /etc/letsencrypt/live/example.com/privkey.pem Your cert will expire on 2019-08-28. To obtain a new or tweaked version of this certificate in the future, simply run certbot again. To non-interactively renew *all* of your certificates, run "certbot renew" - Your account credentials have been saved in your Certbot configuration directory at /etc/letsencrypt. You should make a secure backup of this folder now. This configuration directory will also contain certificates and private keys obtained by Certbot so making regular backups of this folder is ideal. - If you like Certbot, please consider supporting our work by: Donating to ISRG / Let's Encrypt: https://letsencrypt.org/donate Donating to EFF: https://eff.org/donate-le

      We've got our certificates. Let's take a look at what we downloaded and how to use the files with our software.

      Step 3 — Configuring Your Application

      Configuring your application for SSL is beyond the scope of this article, as each application has different requirements and configuration options, but let's take a look at what Certbot has downloaded for us. Use ls to list out the directory that holds our keys and certificates:

      • sudo ls /etc/letsencrypt/live/example.com

      Output

      cert.pem chain.pem fullchain.pem privkey.pem README

      The README file in this directory has more information about each of these files. Most often you'll only need two of these files:

      • privkey.pem: This is the private key for the certificate. This needs to be kept safe and secret, which is why most of the /etc/letsencrypt directory has very restrictive permissions and is accessible by only the root user. Most software configuration will refer to this as something similar to ssl-certificate-key or ssl-certificate-key-file.
      • fullchain.pem: This is our certificate, bundled with all intermediate certificates. Most software will use this file for the actual certificate, and will refer to it in their configuration with a name like 'ssl-certificate'.

      For more information on the other files present, refer to the "Where are my certificates" section of the Certbot docs.

      Some software will need its certificates in other formats, in other locations, or with other user permissions. It is best to leave everything in the letsencrypt directory, and not change any permissions in there (permissions will just be overwritten upon renewal anyway), but sometimes that's just not an option. In that case, you'll need to write a script to move files and change permissions as needed. This script will need to be run whenever Certbot renews the certificates, which we'll talk about next.

      Step 4 — Handling Certbot Automatic Renewals

      Let's Encrypt's certificates are only valid for ninety days. This is to encourage users to automate their certificate renewal process. The certbot package we installed takes care of this for us by adding a renew script to /etc/cron.d. This script runs twice a day and will renew any certificate that's within thirty days of expiration.

      With our certificates renewing automatically, we still need a way to run other tasks after a renewal. We need to at least restart or reload our server to pick up the new certificates, and as mentioned in Step 3 we may need to manipulate the certificate files in some way to make them work with the software we're using. This is the purpose of Certbot's renew_hook option.

      To add a renew_hook, we update Certbot's renewal config file. Certbot remembers all the details of how you first fetched the certificate, and will run with the same options upon renewal. We just need to add in our hook. Open the config file with you favorite editor:

      • sudo nano /etc/letsencrypt/renewal/example.com.conf

      A text file will open with some configuration options. Add your hook on the last line:

      /etc/letsencrypt/renewal/example.com.conf

      renew_hook = systemctl reload rabbitmq
      

      Update the command above to whatever you need to run to reload your server or run your custom file munging script. Usually, on Debian, you’ll mostly be using systemctl to reload a service. Save and close the file, then run a Certbot dry run to make sure the syntax is ok:

      • sudo certbot renew --dry-run

      If you see no errors, you're all set. Certbot is set to renew when necessary and run any commands needed to get your service using the new files.

      Conclusion

      In this tutorial, we've installed the Certbot Let's Encrypt client, downloaded an SSL certificate using standalone mode, and enabled automatic renewals with renew hooks. This should give you a good start on using Let's Encrypt certificates with services other than your typical web server.

      For more information, please refer to Certbot's documentation.



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