If you are running a NodeJS site via Nginx then you may be using proxy_pass to route requests from Nginx to Node.

If you’d like to also prevent hot linking then you might like to first have a read of Marcel Eichner’s post on preventing hot linking which this post is based on.

Then you can use a slightly modified version of that code which includes the proxy_pass directive in both of the location sections.

server {
    server_name yourdomain.com www.yourdomain.com;
    location ~* (\.jpg|\.png|\.gif)$ {
        valid_referers none blocked yourdomain.com www.yourdomain.com ~\.google\. ~\.yahoo\. ~\.bing\. ~\.facebook\. ~\.fbcdn\.;
        if ($invalid_referer) {
            return 403;
        }
        proxy_pass http://127.0.0.1:8123;
    }
    location / {
        proxy_pass http://127.0.0.1:8123;
    }
}

Some notes about this code:

In the valid_referers line, ‘blocked’ allows Referers that have been blocked by a firewall, ‘none’ allows requests with no Referer.

This is then followed by a list of domains and domain patterns that are also allowed. Google, Bing, etc are allowed for their image bots to access your site.