AWS OpenVPN & Let’s Encrypt

Mike Garde
Jan 16 · 2 min read

So you’ve launched a new EC2 running OpenVPN, you’ve SSH’ed in and completed the setup. You can connect to the admin UI but get a warning about the certificate, this is completely safe but annoying. For me it was a bit more complicated because we wanted to transition our development urls to our new 3 letter .dev domain. And you know how this complicates things… so let’s encrypt.

SSH back in and install Let’s Encrypt certbot

sudo apt-get install software-properties-common
sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update
sudo apt-get install certbot

We’re going to pause OpenVPN, generate a cert, create a symbolic link between the new cert and what OpenVPN uses for it’s cert. Then create a CRON job to renew the cert for us.

sudo service openvpnas stopsudo certbot certonly --standalone --agree-tos --non-interactive \
--email dev@domain.com \
--domains vpn.domain.dev \
--pre-hook 'sudo service openvpnas stop' \
--post-hook 'sudo service openvpnas start'
sudo ln -s -f /etc/letsencrypt/live/vpn.domain.dev/cert.pem /usr/local/openvpn_as/etc/web-ssl/server.crtsudo ln -s -f /etc/letsencrypt/live/vpn.domain.dev/privkey.pem /usr/local/openvpn_as/etc/web-ssl/server.keysudo service openvpnas start

Except for the first and last command be sure to use your domain. Finally we create a CRON job to renew the domain. I’ve selected to run it every 3rd month. https://crontab.guru/#0_4_1_*/3_*

sudo crontab -e

And add this command

0 4 1 */3 * sudo certbot -q renew

The pre/post hooks we defined initially were not honored during the creation of the cert, hence why we also performed the operation, instead they are honored during the renewal.

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