Tag Archives forssl

404 Not found on SSL certificate renew with certbot from letsencrypt

I spend a lot of time figuring out why I kept getting a ‘404 Not Found’ when I wanted to renew my SSL Certificate with certbot.

Long story short: invalid ipv6 DNS Mapping.

I got it working by removing the ipv6 DNS entry. I’ll be fixing it in a proper way when there is more time available.

But there were other gotcha’s as well:

  • basic auth on the directory
  • iptables blocking certain traffic



Free SSL certificates with LetsEncrypt

Getting your website on https can be done in a matter of minutes. So there is no excuse anymore to go without it. Not even on your test and dev websites.

As this example is on CentOS, it really goes for any other linux distro.

Excellent, tailor-made instructions per webserver and OS are found on the website of Certbot:

Here, a short recap of that for my own archive.

You’ll need the repel repository for this. After that, install the certbot software.

$ sudo yum install epel-release
$ sudo yum install certbot-nginx


Getting your website secured with SSL is now as simple as answering some questions on the following command.

Note: I’m using a method which takes a bit of downtime because LetsEncrypt is in the middle of an update. Read all about it

$ sudo certbot --authenticator standalone --installer nginx --pre-hook "service nginx stop" --post-hook "service nginx start"

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator standalone, Installer nginx
Which names would you like to activate HTTPS for?
1: yoursite.pauledenburg.com
Select the appropriate numbers separated by commas and/or spaces, or leave input
blank to select all options shown (Enter 'c' to cancel): 2

Running pre-hook command: service nginx stop
Error output from service:
Redirecting to /bin/systemctl stop nginx.service
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for es.git.innospense.com
Waiting for verification...
Cleaning up challenges
Running post-hook command: service nginx start
Error output from service:
Redirecting to /bin/systemctl start nginx.service
Deployed Certificate to VirtualHost /etc/nginx/sites-enabled/yoursite.pauledenburg.com.conf for set(['yoursite.pauledenburg.com'])
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): 2
Redirecting all traffic on port 80 to ssl in /etc/nginx/sites-enabled/yoursite.pauledenburg.com.conf
Congratulations! You have successfully enabled https://yoursite.pauledenburg.com
You should test your configuration at:
 - Congratulations! Your certificate and chain have been saved at:
   Your key file has been saved at:
   Your cert will expire on 2018-04-24. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot again
   with the "certonly" option. To non-interactively renew *all* of
   your certificates, run "certbot renew"
 - 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


Things which might throw you an error

python-urllib3 version

First caveat for CentOS7 is that you need specific version 1.21 for urllib3. I had 1.22 installed via yum which gave me the following error.

ImportError: No module named 'requests.packages.urllib3'

You can see the currently installed version with pip:

pip freeze | grep urllib

To resolve this, first remove the old version it with yum and then add it with pip:

sudo yum remove python-urllib3 
sudo pip install -Iv https://github.com/shazow/urllib3/archive/1.21.1.tar.gz

pyOpenSSL version

Just like urllib3, pyOpenSSL was of an unsupported version.

sudo yum remove pyOpenSSL
sudo pip install pyOpenSSL

Error message stating that the CA can’t be satisfied

After running

certbot --nginx

you get the following error:

Client with the currently selected authenticator does not support any combination of challenges that will satisfy the CA.

Due to legal reasons there currently is no

From the github certbot website:

If you’re serving files for that domain out of a directory on Nginx, you can run the following command:

# Webroot method
$ sudo certbot --authenticator webroot --installer nginx \
  --webroot-path <path to served directory> -d <domain>

If you’re not serving files out of a directory (for instance if you are using proxy_pass), you can temporarily stop your server while you obtain the certificate and restart it after Certbot has obtained the certificate. This would look like:

# Temporary outage method
$ sudo certbot --authenticator standalone --installer nginx \
  -d <domain> --pre-hook "service nginx stop" --post-hook "service nginx start"