Enable directory listing nginx ubuntu 16..04

para habilitar el index usamos lo siguiente

nano /etc/nginx/sites-enabled/default

#!/bin/bash
server {
        listen   80;
        server_name  domain.com www.domain.com;
        access_log  /var/...........................;
        root   /path/to/root;
        location / {
                index  index.php index.html index.htm;
        }
        location /somedir {
               autoindex on;
        }
}

Fuente: http://nginxlibrary.com/enable-directory-listing/