worker_processes  3;
pid logs/nginx.pid;

events 
{
    worker_connections  1024;
}

http 
{
    access_log off;
    error_log off;

    include    mime.types;
    default_type    application/octet-stream;

    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
        '$status $body_bytes_sent "$http_referer" '
        '"$http_user_agent"';

    # Кофиг для сайтов, кроме того где идет раздача файлов
    server 
    {
        access_log off;
        error_log off;

        listen xxx.xxx.212.106:80;
        server_name *.*;

        location / 
        {
            proxy_pass http://xxx.xxx.212.106:8181/;
            proxy_redirect    off;

            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }
    }

    # Кофиг для сайта где осуществляется раздача
    server
    {
        access_log off;
        error_log off;

        listen xxx.xxx.212.106:80;
        server_name xxx.com;

        location /
        {
            proxy_pass http://xxx.xxx.212.106:8181/;
            proxy_redirect off;

            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }

        location /data {
                root /usr/home/admin/domains/xxx.com/public_html;
                internal;
            }
    }
}

<?
header("Content-Disposition: attachment; filename=test.pdf");
header("X-Accel-Redirect: /data/storage/1/test.pdf");
?>

/usr/home/admin/domains/xxx.com/public_html/data/storage/1/test.pdf