pikvm/docs/letsencrypt.md

Let's Encrypt certificates

PiKVM uses self-signed SSL certificates out of the box. If you have a domain name, you can use Let's Encrypt certificates.

Usually Let's Encrypt certificates are issued and updated automatically using Certbot, however, since PiKVM uses a read-only file system, special tools around Certbot are required to work with certificates. KVMD 3.117 provides them.

!!! note This feature is available on images as old as 2022.06.19 since it requires PST storage partition on SD card. Ports 80+443 need to be opened if you are port forwarding for this to work properly.

Basic setup

1. Update the OS and make sure that you are using a new image with PST storage.

   # rw
   # pacman -Syu
   # reboot
   ...
   # kvmd-pstrun -- true
   

   If the storage is not available, you need to reflash the OS image to the latest one from our official website.

2. Switch filesystem to RW and obtain the certificate (for example, pikvm.example.com. The method depends on the network configuration. In the simplest case, if PiKVM is open for access from the Internet, it is recommended to use the webroot. Another examples will be described below.

   # rw
   # kvmd-certbot certonly_webroot --agree-tos -n --email user@example.com -d pikvm.example.com
   

3. Install the certificate for KVMD-Nginx and (optionally) KVMD-VNC. Running services will be restarted/reloaded automatically. Switch filesystem to RO.

   # kvmd-certbot install_nginx pikvm.example.com
   # kvmd-certbot install_vnc pikvm.example.com
   # ro
   

4. Check the renewal immediately, just for testing:

   # kvmd-certbot renew --force-renewal
   

5. Enable automatic certificate renewal:

   # rw
   # systemctl enable --now kvmd-certbot.timer
   # ro
   

Cloudflare DNS

This example shows that PiKVM may not be accessible from the internet, but you can still get a certificate if you use Cloudflare DNS.

1. Switch filesystem to RW and install the Cloudflare DNS plugin:

   # rw
   # pacman -S certbot-dns-cloudflare
   

2. Prepare the environment for the DNS plugin (place the auth data):

   # kvmd-pstrun -- mkdir -p /var/lib/kvmd/pst/data/certbot/runroot
   # kvmd-pstrun -- nano /var/lib/kvmd/pst/data/certbot/runroot/.cloudflare.auth
   # kvmd-pstrun -- chmod 600 /var/lib/kvmd/pst/data/certbot/runroot/.cloudflare.auth
   

3. Obtain the certificate:

   # kvmd-certbot certonly \
      --dns-cloudflare \
      --dns-cloudflare-propagation-seconds 60 \
      --dns-cloudflare-credentials /var/lib/kvmd/pst/data/certbot/runroot/.cloudflare.auth \
      --agree-tos \
      -n \
      --email user@example.com \
      -d pikvm.example.com
   

4. Next follow the basic guide.

Route53 DNS

This example shows that PiKVM may not be accessible from the internet, but you can still get a certificate if you use AWS Route53 DNS. Make sure you are running an image newer than 2022.06.20 and kvmd version 3.119-1 or greater.

1. Switch filesystem to RW and install the Route53 DNS plugin:

   # rw
   # pacman -S certbot-dns-route53
   

2. Configure Your AWS User For the certbot_dns_route53 plugin to work it needs to be able to connect to AWS using an access key with the correct permissions.

   To do this securely you’ll want to create a new AWS user that only has the necessary permissions it needs to work.

   You can find instructions for creating a user here. The basics of it is you’ll want a user with Programmatic access (not console), add it to a group (I created a new one just for this user and any future certbot users I might need).

   The user will need specific permissions that are required to allow the certbot plugin to create the necessary CNAME records. These can be added by manually selecting them from a very long list or you can use the json view to give it the following permissions.

   {
   "Version": "2012-10-17",
   "Statement": [
      {
         "Effect": "Allow",
         "Action": ["route53:ListHostedZones", "route53:GetChange"],
         "Resource": ["*"]
      },
      {
         "Effect": "Allow",
         "Action": ["route53:ChangeResourceRecordSets"],
         "Resource": ["arn:aws:route53:::hostedzone/YOURHOSTEDZONEID"]
      }
   ]
   }
   

   Make sure you replace YOURHOSTEDZONEID with the instance ID of your hosted zone.

   Once the user is created don’t forget to download and save your access key and secret access key (somewhere secure, these are as sensitive as your passwords).

3. Setup credentials:

   We now need to put the AWS credentials on the PiKVM so the certbot can use them.

   # kvmd-pstrun -- mkdir -p /var/lib/kvmd/pst/data/certbot/runroot
   

   Copy and paste your AWS credentials into the nano editor and save the file.

   # kvmd-pstrun -- nano /var/lib/kvmd/pst/data/certbot/runroot/.route53.auth
   

   Here is an example .route53.auth file. Replace the placeholders with the access key and secret access key that you just saved from AWS and fill them in.

   [default]
   aws_access_key_id=XXXXXX
   aws_secret_access_key=XXXX/XXXXX
   

   Update permissions:

   # kvmd-pstrun -- chmod 600 /var/lib/kvmd/pst/data/certbot/runroot/.route53.auth
   

4. Obtain the certificate:

   # export AWS_SHARED_CREDENTIALS_FILE="/var/lib/kvmd/pst/data/certbot/runroot/.route53.auth"
   # kvmd-certbot certonly \
      --dns-route53 \
      --agree-tos \
      -n \
      --email user@example.com \
      -d pikvm.example.com
   

5. Enable automatic certificate renewal:

   Create the file: /etc/conf.d/kvmd-certbot with the following contents so the renewall service can find the authentication file containing the AWS credentials:

   AWS_SHARED_CREDENTIALS_FILE="/var/lib/kvmd/pst/data/certbot/runroot/.route53.auth"
   

   Now enable the renewal service:

   # systemctl enable --now kvmd-certbot.timer
   

ACME DNS

ACME DNS is a "Limited DNS server with RESTful HTTP API to handle ACME DNS challenges easily and securely." The acme-dns-client works, in conjunction, with Certbot (kvmd-certbot) to enable DNS-01 challenge support via ACME DNS.

These instructions are for how to install and use the acme-dns-client with ACME DNS for PiKVM.

Assumptions

• ACME DNS is already set up and functioning in the environment
• ACME DNS Server is auth.example.org
• PiKVM Fully Qualified Domain Name (FQDN) is pikvm.example.org
• PiKVM is running on a supported Raspberry Pi using the PiKVM OS (which is 32-bit as of the writing of this documentation)
• All configuration examples below are as user root via a terminal session to PiKVM

Not in Scope

• Installation and Setup of ACME DNS Server

Instructions

1. Ensure that Step 1 from Basic Setup has been completed

2. Visit the Releases page to get the download URL for the latest acme-dns-client release (PiKVM OS is 32-bit, which is linux_armv6)

3. Install acme-dns-client

   The acme-dns-client is not distributed by pacman and is a manual installation. The steps below are for:

   • Creating a folder for acme-dns-client
   • Downloading and extracting the acme-dns-client TAR from Github
   • Moving the acme-dns-client binary to the created folder
   • Cleaning up files from the download
   • Creating the necessary persistent symbolic link to allow acme-dns-client to be ran
   • Initialize acme-dns-client

   !!! note Make sure to replace the URL below with the one gathered from Step 1.
   As of the writing of this documentation:
   - The latest (and demonstrated) version is v0.3
   - (Demonstrated) Platform is linux-armv6

   # mkdir /etc/acmedns
   # curl -LO https://github.com/acme-dns/acme-dns-client/releases/download/v0.3/acme-dns-client_0.3_linux_armv6.tar.gz
   # tar -zxvf acme-dns-client_0.3_linux_armv6.tar.gz
   # mv acme-dns-client /etc/acmedns/acme-dns-client
   # ln -sf /etc/acmedns/acme-dns-client /usr/local/bin/acme-dns-client
   # rm LICENSE README.md acme-dns-client_0.3_linux_armv6.tar.gz
   # acme-dns-client
   

4. Register acme-dns-client with ACME DNS

   !!! note This is interactive, follow instructions for creating and verifying the appropriate CNAME record.

   # acme-dns-client register -d pikvm.example.org -s http://auth.example.org
   

   Once registration is complete ownership of clientstorage.json must be changed to kvmd-certbot.

   # chown kvmd-certbot:kvmd-certbot /etc/acmedns/clientstorage.json
   

   !!! note If using acme-dns-client on an internal/private domain with an ACME compatible Certificate Authority do not forget to add -ns <dns-server-ip>:<dns-server-port> to acme-dns-client register

5. Register Certbot

   # kvmd-certbot register
   

6. Request Certificate via Certbot

   # kvmd-certbot certonly --manual --preferred-challenges dns --manual-auth-hook 'acme-dns-client' -d pikvm.example.org
   

   !!! note If using an ACME compatible Certificate Authority (other than Let's Encrypt) do not forget to add --server https://ca.example.org/acme/acme/directory to kvmd-certbot

7. Follow steps 3 through 5 under Basic Setup to complete setup and renewal of certificates

Wireguard proxy

If you don't have public IP, and you don't want to put your API keys in PiKVM, you can forward HTTP traffic over wireguard. To Let's Encrypt you'll appear to serve ACME challenges from a host they can reach from the Internet (e.g. VPS), to which you'll connect over wireguard.

Assumptions

• FQDN of your pikvm is pikvm1.int.example;
• FQDN of the proxy VPS is acme-proxy.example;
• public IP addresses of VPS are 198.51.100.1 and 2001:db8::1;
• internal (wireguard) IPv4 address of the PiKVM is 10.11.12.13.

Instructions

1. Setup wireguard and ensure it's working.

2. Setup public DNS zone to point the domain address at the public VPS:

   acme-proxy.example. IN A      198.51.100.1
   acme-proxy.example. IN AAAA   2001:db8::1
   pikvm1.int.example. IN CNAME  acme-proxy.example.
   

3. On the public VPS, configure HTTP proxy to forward /.well-known/acme-challenge to PiKVM. For example in nginx:

   server {
      listen 80;
      listen [::]:80;
   
      server_name pikvm1.int.example;
   
      location ^~ /.well-known/acme-challenge {
         proxy_pass http://10.11.12.13:80;
         proxy_set_header Host $host;
      }
   
      location / {
         return 404;
      }
   }
   

4. Now you can use kvmd-certbot certonly_webroot as in basic scenario above.