Captcha can be enabled for this home server. This file explains how to do that. The captcha mechanism used is Google's ReCaptcha. This requires API keys from Google.
Requires a public/private key pair from:
https://developers.google.com/recaptcha/
The keys are a config option on the home server config. If they are not visible, you can generate them via --generate-config. Set the following value:
recaptcha_public_key: YOUR_PUBLIC_KEY recaptcha_private_key: YOUR_PRIVATE_KEY
In addition, you MUST enable captchas via:
enable_registration_captcha: true
The ReCaptcha API requires that the IP address of the user who solved the captcha is sent. If the client is connecting through a proxy or load balancer, it may be required to use the X-Forwarded-For (XFF) header instead of the origin IP address. This can be configured as an option on the home server like so:
captcha_ip_origin_is_x_forwarded: true