How To Secure Nginx with Let’s Encrypt SSL on Debian 9

Install Let’s Encrypt on Debian

By using Let’s Encrypt you can get a free valid SSL certificate. Let’s Encrypt is the Certificate Authority (CA) which provides free SSL certificate. To get SSL certificate Certbot client is used which fetches and deploys SSL certificate on your server. In this tutorial, you are going to learn how to install Let’s Encrypt SSL on Debian 9.

Before we begin

Let’s Encrypt certificate can only be requested from the server the domain is pointing to. Let’s Encrypt checks if the domain is pointed to the current server and if successful, it issues the certificate.


1. Before you start to install Let’s Encrypt SSL on Debian 9 using the Certbot client. You must have the non-root user account on your server with sudo privileges.

2. Make it sure your domain is pointing to the current server.

1. Install Certbot Client

To install Certbot client you need to add PPA on the server then you will need to update the package manager index. After that, you will install the Certbot client.

Add PPA by typing following in the terminal

sudo add-apt-repository ppa:certbot/certbot

Update package manager index by typing following

sudo apt update

Now install Certbot client by executing following command

sudo apt install python-certbot-nginx

Confirm the installation by typing

certbot --version

2. Setting Up Firewall

If you have enabled UFW firewall then you need to adjust the settings to allow HTTPS traffic.

To check current status type following command

sudo ufw status
Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Nginx HTTP                 ALLOW       Anywhere                  
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Nginx HTTP (v6)            ALLOW       Anywhere (v6)

Now to get HTTPS traffic in, you should add ‘WWW Full’ rule and delete ‘WWW’ rule which will become redundant.

sudo ufw allow 'Nginx Full'
sudo ufw delete allow 'Nginx HTTP'

Now the status should be:

Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Nginx Full                 ALLOW       Anywhere                  
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Nginx Full (v6)            ALLOW       Anywhere (v6)

3. Setting up Let’s Encrypt SSL on Nginx

Let’s Encrypt do a strong domain validation for ownership of the domain. After successful verification, it issues the certificate. In below command replace example with your domain name

sudo certbot --nginx -d -d

If you are first time installing certificate then Certbot will ask you to enter Email ID and agree terms and conditions.

After above step Certbot will ask you to configure HTTPS settings.

Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
1: No redirect - Make no further changes to the webserver configuration.
2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
Select the appropriate number [1-2] then [enter] (press 'c' to cancel):

Select your choice and continue to next step. We recommend to choose Redirect Option if you dont want to modify configuration file manually.

5. Autorenewal For SSL Certificates

All of these Let’s Encrypt certificates are short-lived and expires after 90 days. So you will have to update these certificates before they expire by running the following command.

sudo certbot renew

You can automate this process by adding a cronjob. Enter the following command to open crontab

sudo crontab -e

Add following lines to end of the file. It will run the command twice a day and renews if the certificate is about to expire.

0 */12 * * * root test -x /usr/bin/certbot -a \! -d /run/systemd/system && perl -e 'sleep int(rand(43200))' && certbot -q renew

4. Installing Let’s Encrypt Wildcard Certificates

Let’s Encrypt now supports wildcard certificate using new ACME2 protocol. By using wildcard certificate \* like this, you can use one certificate for multiple sub-domains like,, etc. To install the wildcard certificate type following command.

sudo certbot certonly --manual -d * --agree-tos --no-bootstrap --manual-public-ip-logging-ok --preferred-challenges dns-01 --server

NOTE: Now you will see the message at center in output to add TXT record. So make DNS changes to your domain and add specific TXT record with given value inside output of above command


You have learned how to install Let’s Encrypt SSL on Debian 9 by using Certbot. If you have any queries regarding this please don’t forget to comment below.