server  
{  
    listen    80;  
    server_name download.jb51.net;  
    index index.htm index.html;  
    root /data/www/download;  
    ssi on;  
 
    location /  
    {  
        set_by_lua $downkey '  
            return ngx.md5("encryption" .. ngx.var.remote_addr .. "suffix")  
        ';  
    }  
} 

server  
{  
    listen    80;  
    server_name down.jb51.net;  
    index index.htm index.html;  
    root /data/www/down;  
    limit_conn  one 1;  
    set $limit_rate 1000k;  
 
  location /  
    {  
        set_by_lua $foo '  
            if string.sub(ngx.var.uri, 2, 33) == ngx.md5("encryption" .. ngx.var.remote_addr .. "suffix") then  
                return 1 
            else 
                return 0 
            end  
        ';  
 
        if ($foo = 1)  
        {  
            rewrite "^/([0-9a-z]{32})(.*?)$"    $2 break;  
        }  
        if ($foo = 0)  
        {  
            rewrite ^/ http://download.jb51.net/404.htm redirect;  
        }  
    }  
}