upstream backend-site.com {server unix:/var/run/php5-site.com.sock;}

server {
    listen              80;
    server_name         site.com [url=http://www.site.com]www.site.com[/url];
    root                /var/www/user/site.com/web;

    rewrite ^/app\.php/?(.*)$ /$1 permanent;

    location / {
        index app.php;
        try_files $uri @rewriteapp;
    }

    location @rewriteapp {
        rewrite ^(.*)$ /app.php/$1 last;
    }

    location ~ ^(.+\.php)($|/) {
        fastcgi_split_path_info ^(.+\.php)(.*)$;
        include fastcgi_params;
        fastcgi_param  SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_pass backend-site.com;
    }
}