CertGetter

Proper SSL certificates can only be assigned to machines with Internet accessible FQDNs (Fully Qualified Domain Names). On an internal network, this causes all sorts of annoying problems since modern browsers actively oppose insecure connections (& even a self-signed certificate is considered insecure.)

If your internal network is set up to use your actual domain, This is a way to get certs for machines that are not accessible from the outside world.

These certs will expire & cannot be renewed automatically, but can be renewed using this same basic procedure. (simply running it again) You can also renew all of the certs this machine has obtained with sudo certbot renew

Certbot Documentation

Setting Up

• Create a Baseline Server
• Install certbot
  • sudo apt-get install certbot

Usage

• Assign port 80 to this machine on your firewall
• Assign DNS for the name of the machine you're obtaining certs for
• Wait for the DNS entry to propagate
  • You can repeatedly try systemd-resolve machinename.yourdomain.net until it shows your outside address...
  • (Tho, you might need to do this from outside your local network.)
• Run certbot
  • sudo certbot certonly --standalone --dry-run
    • (Always test first with --dry-run)
    • Then run it again if all is ok but without --dry-run
• You will find the resulting certs in /etc/letsencrypt/live/ in a subfolder matching the machine name you gave certbot.
• fullchain.pem is the certificate
• privkey.pem is the key
• Then simply copy fullchain.pem & privkey.pem (following the procedures for the OS involved) the cert to the machine in need.
• It is a good idea to disconnect port 80 from this machine when not in use. (especially if you have an actual webserver...

Interim Notes

• To copy certs for a machine to your proxy server
  • First, make sure you can SSH into the proxy server from CertGetter
    • ssh webserver
    • then exit when you've succeeded (this tells CertGetter how to get there...)
  • Then you can use scp to copy the certs.
    • scp -r /etc/letsencrypt/live/Machine.Domain.TLD user@webserver:~
  • Then ssh back into the proxy server & move the certs into their proper location
  • sudo mv Machine.Domain.TLD /etc/letsencrypt/live/

Coming Soon...

I am currently working on a script or 6 to make CertGetter automatically renew certs & push them to the appropriate machines. Watch this space.