Notes on setting up letsencrypt

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Setup letsencrypt
Generate certificates
Update web server configuration

Below are some notes when setting it up in two different systems, in Centos 6.7 with Apache and in Centos 7 with Nginx and Varnish

Centos 6.7 with Apache

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Initial setup: ./letsencrypt-auto --help
Generate keys: ./letsencrypt-auto --apache


Checking for new version...
Creating virtual environment...
./letsencrypt-auto: line 455: virtualenv: command not found

To fix the above, we need to install the missing dependencies. ( for more info see:

yum install centos-release-SCL
yum update
yum install scl-utils python27 python27-scldevel
scl enable python27 bash

Now we should be able to generate the keys by running:
./letsencrypt-auto --apache

Note: In future key generation we only need to run: scl enable python27 bash

If the generation has been successful, we should see a message showing where the certificates are stored. By default should be in:


So now we can update the Apache vhost with:

<VirtualHost *:443>

SSLEngine on
   SSLCertificateFile /etc/letsencrypt/live/
   SSLCertificateKeyFile /etc/letsencrypt/live/
   SSLCertificateChainFile /etc/letsencrypt/live/


If SSL not configured correctly, the following steps may help:

  • Add the ssl.conf (or equivalent in httpd.conf)
  • Remove the example from ssl.conf
  • If there are issues with port not accessible, check using: netstat -nlt
  • May need to enable in iptables, although might just be that apache is not Listening
  • Failed to connect to host for DVSNI challenge: Needed to use the full url

If getting warning: _default_ VirtualHost overlap on port 443, the first has precedence

Do something like:

NameVirtualHost *:443
Listen 443

Once that's working, we can set a redirect to 443 from port 80

<VirtualHost *:80>

    Redirect /


Centos 7 with Nginx and Varnish

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Initial setup: ./letsencrypt-auto --help

./letsencrypt-auto certonly -a webroot --webroot-path=/srv/public -d -d

Under nginx configuration (e.g. /etc/nginx/sites-available/default.conf)
Add a server section for a redirect (note we’re using Varnish):

server {
        listen 8080;


        return 301 https://$host$request_uri;

And a second server section to include all the other info:
Listen for port 8080 (because we’re using Varnish) and port 443.
Add location with the 443 configuration.

server {

        listen 8080;


        listen 443 ssl default;

        ssl_certificate /etc/letsencrypt/live/;
        ssl_certificate_key /etc/letsencrypt/live/;


       location / {
            try_files $uri $uri/ /index.php?$query_string;
            proxy_set_header X-Real-IP  $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto https;
            proxy_set_header X-Forwarded-Port 443;
            proxy_set_header Host $host;

In case SSL not configured correctly, check if web server is listening on port 443.
netstat -nlt

If 443 not showing check web server configuration. Otherwise check if https is accessible internally:
curl -I

If it is accessible internally but not externally, check the firewall:

iptables -A INPUT -p tcp -m state --state NEW -m tcp --dport 443 -j ACCEPT
service iptables save
service iptables restart


firewall-cmd --add-port=443/tcp
firewall-cmd --permanent --add-port=443/tcp

As we are running Varnish, very important to restart both services:

systemctl restart nginx.service
systemctl restart varnish.service

Certificate Renewals

Certificates are only valid for 90 days. Checkout Cal Evan’s post on automating the renewal process: