SSL certificates

ssl-certificates

Overview

HTTPS prevents network attackers from observing or injecting page contents. This is desirable for server applications like RaspAP — or indeed any locally hosted web application. But HTTPS requires TLS certificates, and while deploying public websites is largely a solved issue thanks to the ACME protocol and Let's Encrypt, local web servers still mostly use HTTP because no one can get a universally valid certificate for localhost.

Locally trusted certificates

Managing your own Certificate Authority (CA) is the best solution, but this usually requires an involved manual setup routine. An excellent solution for local websites is mkcert. This is a zero-config tool for making locally-trusted certificates with any name you like. mkcert automatically creates and installs a local CA in the system root store and generates locally-trusted certificates. It also works perfectly well with RaspAP. This allows you to generate a trusted certificate for a hostname (for example, raspap.local) or IP address because it only works for you.

raspap.local

Here's the twist: it doesn't generate self-signed certificates, but certificates signed by your own private CA. This tool does not automatically configure servers or mobile clients to use the certificates, though — that's up to you. These steps are covered in detail below.

Read more about mkcert here and follow the project on GitHub.

Creating a certificate

There are two options to go about creating a self-signed certificate with mkcert: 1) manually, or 2) with the Quick installer. Both methods are described below.

Manual steps

Follow the steps below to generate and install a locally-trusted certificate for RaspAP. The local domain raspap.local is used in the examples below. You may substitute this with the default raspberrypi.local or your own hostname.

Tip

If you've changed your hostname prior to starting this process, be sure to reboot your device for the change to take effect.

Start by installing the pre-built binary for Arch Linux ARM on your Raspberry Pi:

sudo wget https://github.com/FiloSottile/mkcert/releases/download/v1.3.0/mkcert-v1.3.0-linux-arm -O /usr/local/bin/mkcert
sudo chmod +x /usr/local/bin/mkcert
mkcert -install

You should see output like the following:

Using the local CA at "/home/pi/.local/share/mkcert" ✨
The local CA is now installed in the system trust store! ⚡️

Generate a certificate for raspap.local:

cd /home/pi
mkcert raspap.local "*.raspap.local" raspap.local

You should see output like the following:

Using the local CA at "/home/pi/.local/share/mkcert" ✨

Created a new certificate valid for the following names 📜
 - "raspap.local"
 - "*.raspap.local"
 - "raspap.local"

Reminder: X.509 wildcards only go one level deep, so this won't match a.b.raspap.local ℹ️
The certificate is at "./raspap.local+2.pem" and the key at "./raspap.local+2-key.pem" ✅

Next, combine the private key and certificate:

cat raspap.local+2-key.pem raspap.local+2.pem > raspap.local.pem

Create a directory for the combined .pem file in lighttpd:

sudo mkdir /etc/lighttpd/ssl

Set permissions and move the .pem file:

chmod 400 /home/pi/raspap.local.pem
sudo mv /home/pi/raspap.local.pem /etc/lighttpd/ssl

Edit the lighttpd configuration with sudo nano /etc/lighttpd/lighttpd.conf. Add the following block to enable SSL with your new certificate:

server.modules += ("mod_openssl")
$SERVER["socket"] == ":443" {
  ssl.engine = "enable"
  ssl.pemfile = "/etc/lighttpd/ssl/raspap.local.pem"
  ssl.ca-file = "/home/pi/.local/share/mkcert/rootCA.pem"
  server.name = "raspap.local"
  server.document-root = "/var/www/html"
}

Optionally, you can redirect all HTTP requests to HTTPS like so:

$SERVER["socket"] == ":80" {
  $HTTP["host"] =~ "(.*)" {
    url.redirect = ( "^/(.*)" => "https://%1/$1" )
  }
}

Save your changes and quit out of the editor with Ctrl+X followed by Y and finally Enter.

Restart the lighttpd service:

sudo systemctl restart lighttpd

Verify that lighttpd has restarted without errors:

sudo systemctl status lighttpd

You should see a response like the following:

● lighttpd.service - Lighttpd Daemon
     Loaded: loaded (/lib/systemd/system/lighttpd.service; enabled; vendor preset: enabled)
     Active: active (running) since Sun 2023-03-26 10:09:46 CEST; 5 days ago
   Main PID: 1080 (lighttpd)
      Tasks: 6 (limit: 779)
        CPU: 5min 17.332s
     CGroup: /system.slice/lighttpd.service
             ├─1080 /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf
             ├─1168 /usr/bin/php-cgi
             ├─1185 /usr/bin/php-cgi
             ├─1186 /usr/bin/php-cgi
             ├─1187 /usr/bin/php-cgi
             └─1188 /usr/bin/php-cgi

Mar 30 18:23:38 raspap lighttpd[1433]: Syntax OK
Mar 30 18:23:38 raspap systemd[1]: Started Lighttpd Daemon.

Now, copy rootCA.pem to your lighttpd web root:

sudo cp /home/pi/.local/share/mkcert/rootCA.pem /var/www/html

Important

Do not share the rootCA-key.pem file.

Finish by following the client configuration steps below.

Quick installer

The Quick Installer may also be used to generate SSL certs with mkcert. The installer automates the manual steps described above, including configuring lighttpd with SSL support. It's recommended to review these steps to have an idea of what is happening behind the scenes.

Invoke the Quick installer and specify the -c or --cert option, like so:

curl -sL https://install.raspap.com | bash -s -- --cert

Note

Executing the Quick installer only installs mkcert and generates an SSL certificate with the input you provide. It does not (re)install RaspAP.

The installer will walk you through the steps of creating a certificate. Complete the installation by following the client configuration steps below.

Client configuration

Open a browser and enter the following address, substituting the domain name you chose in the steps above: http://raspap.local/rootCA.pem. Download the root certificate to your client and add it to your system keychain. Examples below illustrate this process on macOS:

Be sure to set this certificate to "Always trust" to avoid browser warnings.

Finally, enter the address https://raspap.local in your browser. Enjoy an encrypted SSL connection to RaspAP.

Mobile devices

For the certificates to be trusted on mobile devices and remote clients, you will have to install the root CA using the method described above. Alternatively, on iOS, you can either use AirDrop or email the CA to yourself. After installing it, be sure to enable full trust.

More advanced topics are covered at mkcert.

Discussions

Questions or comments about using SSL certificates? Join the discussion here.