How do I prevent public downloads of files using php? - php

I have a script that allows only authorised users to upload files to a certain folder.
However I do not know how to prevent people from downloading freely without login.
I need the solution in php.
I have googled around but nothing straight forward as yet.
Currently in my document root I have a folder called admin and a subfolder called uploads inside the admin. So only admin role can upload. Both editor and admin can download. What should I do in this case?
Please advise.

Put the files somewhere outside the public webroot directory, or configure your server to not serve the files. As long as your server will happily serve everything with a valid URL, there's nothing you can do with PHP to prevent that.
If your files are in the /public_html/ folder, take them out of that folder and place them in e.g. /secret_files/, so your directory structure looks something like this:
public_html/
index.html
admin/
admin_index.php
secret_files/
my_secret_file.txt
The webserver is only configured to serve files in the /public_html/ directory, so nobody will have access to directories outside (technical term above) it.
To still enable somebody to download those files, do as cletus suggests and use readfile to "manually serve" the files via a PHP script. PHP will still have access to these other parts of the file system, so you can use it as a gatekeeper.

Don't store the files in a directory under the document root.
Instead move them somewhere else and then a PHP script can programmatically determine if someone can download them and then use readfile() or something similar to stream them to the user.
You could also configure the Web server to not serve files from this directory but then you need PHP to serve them anyway. It's cleaner simply not to put them under the document root.

Answering question on how to password protect with PHP:
This should solve your problem.

Related

How can I prevent access to my PHP include files like header.php, footer.php and the likes?

I am developing a website for myself and I just wonder how can I prevent direct access to include files like header.php and footer.php. Those files should only be incorporated in pages like index.php or other pages wherein they will be called using <?php include(''); ?>. Should I do it through PHP? How about editing the .htaccess file or are there any other methods?
place the files(s) in a directory out side the web root.
the web server will never serve theses files to users.
php et.al. can still access the files via include\require etc
This has been the gold standard approach for several decades.
I offered 3 suggestions and since you didn't provide much to go one, I will give you one elaboration.
As #Dragon eludes to, when you use include() your reading via the file system and not via a HTTP Request. You can check for an HTTP verb ($_REQUEST, $_GET, $_POST) and refuse to show content or fake a 401.
<?php
if(isset($_REQUEST) || isset($_GET) || isset($_POST)){
header("HTTP/1.0 404 Not Found");
die();
}
// Do the needed
?>
I will let you figure out the gotcha on your own here.
It would be perfect if your server is linux, because then what you can do is follow Dagon's suggestion of placing the files to include outside of the web root.
The web root of course is the base folder that contains files the outside world is meant to access. On many systems, this is the public_html folder.
On a system with WHM/cpanel installed, you might have a special user account where the root of that account (where anything can be stored) is located at /home/user on the entire system. This can be viewed by using the file manager utility included with cpanel when logged in. In that /home/user folder, you may find configuration files and folders starting with a period as well as public_ftp and public_html folders.
In the /home/user folder, you can place the PHP files you don't want the world to directly access. Then In public_html, (accessible within /home/user) you can place the index.php file that has the include statement to the "protected" files. That way in index.php you can use this statement:
include "../file-to-include.php";
Just make sure that the administrator has set the owner of the /home/user folder to the same username you login with or you may get access denied messages when trying to access the file. On a decent cpanel setup, the last step would have already been done for you.

Allowing upload and browse but disallowing download

I think this question should be something easy but after searching all over the web I couldnt find an answer, so I decided to ask here.
I have a file uploader in my website that works with php. The folder where files are being uploaded has 777 chmod. I also have a php script to list the files in that folder. What I need is to allow php to upload and browse files on that folder, but dont allow people to do it. The only solution I imagined is to chown that folder to another user different than default, so I could later chmod in filezilla and allow only owner to do it, so people will see the files trough the output of the php script, but not if they navigate to that folder.
Im using Debian, apache2. Id like to know what could I do.
To make it shor, my aim: allow php to upload, read, write and execute files in that folder, but not clients unless they use my php script.
Thanks in advance
Put all the files you're talking about in their own directory. Add a .htaccess file to that directory. The contents of the .htaccess should be deny from all.
This will prevent any user from manually accessing the files as access will be blocked off. Your PHP script can still browse the contents of the file and serve it up as an attachment with the correct content type.
For more info on how to serve a file for download in PHP, read this: https://serverfault.com/questions/316814/php-serve-a-file-for-download-without-providing-the-direct-link
All services including web servers run in a security context which is an account in the OS, for example apache starts using apache user in apache group. It is enough to change mode and change owner to this user and group. Never chmod a directory to 777 until there is a good explanation for that. Using this trick, web service process only can read, write and execute in that directory.
As well, if you want the browser clients not to see(read) the contents of that directory, you should deny listing on that directory. I think it is disabled for default.

Can I place PHP config files securely in a publicly accessible folder?

GoDaddy does not a give FTP root access to my account, meaning I can only access the public_html folder and not the includes folder.
Is there any way I can include the config files in that public folder but somehow make it so only the server can access them in a secure way? How does Wordpress do it?
You could use a .htaccess file to restrict Website Access.
Take a look of this article.
just make sure they have a .php extension.
(and actually contain PHP code of course)
Wordpress keeps the config file in the main folder. Just make sure you have a .php extension and you dont echo anything from that. (I know you wont.)
People really cant get the details inside your php file unless you echo something, or the chmod of the file is set wrong so that people may be able to actually download the file.
As xdazz said, you can also restrict access to your config files, but I think its just for MORE protection, and you are still safe without that.

folder to save files that are retrieved with require in document tree

I'm building a website based on php and i want to ask where to put files that are retrieved with a require statement, so that they can not be accessed from users with their browser.
(for example a php file that connects to my database)
EDIT actually i think the better way is to put them outside the public root because apache tutorial says htaccess will have a slowdown impact. it can be done with adding a ../
for example require("../myFile.php"); (At least this works in my server)
Best regards to all
That depends on the web server configuration. Usually (or at least in all cases I witnessed), you have a document root which cannot be accessed by users with their browser, with in there a folder containing all public material (often called htdocs, httpdocs, public_html or anything of the kind. Often, you can place your PHP include files in that root, and then require them using require("../include_file.php");
However, it depends on the configuration whether PHP can include files outside your public folder. If not, a .htaccess file is your best option.
If you place those files outside the document root of your webserver users cannot access these files with a browser.
If you use apache you can also place these files in a directory to which you do not allow access with a .htaccess file.
And as a last remark, if your files do not generate output, there is no way users can check the contents of the files.
If you mean source code then it is not visible for users, if you want hide folder contents use .htaccess directive Options -Indexes to hide files, if you can access php source your server configuration is wrong and it is not parsing php files.
You normally place them into a directory that is not accessible over the webserver (outside the document or web root). Sometimes called a "private" directory.
You then include/require the file from that path as PHP has still access to the files.
See also:
placing php script outside website root
disable access to included files - For a method if you're not able to place the files in a private directory.
Just make them secure with .htacces!
Here's a very clear tutorial for protecting files with a password. If you don't need direct access to the files per browser, or only your scripts need access, just block them completly by changing the code between
<Files xy>
change this bit here
</Files>
to
Order allow,deny
Deny from all
Then you won't need your htpassword file anymore either!
You need to put these files outside of public-facing folders on your web server. Most (all?) web hosts should have the capability to change the document root of the website.
For example, let's say that all of your files are served from the following directory on your host: /home/username/www/example.com/
This means that anything that resides inside that directory is visible to the internet. If you went to http://example.com/myfile.png it would serve the file at /home/username/www/example.com/myfile.png.
What you want to do is create a new directory called, for example, public which will serve your files, and point the document root there. After you've done that, the request for http://example.com/myfile.png will be served from /home/username/www/example.com/public/myfile.png (note the public directory here). Now, anything else that resides within the example.com directory won't be visible on your website. You can create a new directory called, for example, private where your sensitive include files will be stored.
So say you have two files: index.php, which serves your website, and sensitive.php which contains passwords and things of that nature. You would set those up like this:
/home/username/www/example.com/public/index.php
/home/username/www/example.com/private/sensitive.php
The index.php file is visible to the internet, but sensitive.php is not. To include sensitive.php, you just include the full file path:
require_once("/home/username/www/example/com/private/sensitive.php");
You can also set your application root (the root of your websites files, though not the root of the publicly accessible files) as a define, possibly in a config file somewhere, and use that, e.g.:
require_once(APP_ROOT . "sensitive.php");
If you can't change the document root, then what some frameworks do is use a define to note that the file shouldn't be executed directly. You create a define in any file you want as an entry point to your application, usually just index.php, like so:
if (!defined('SENSITIVE')) {
define('SENSITIVE', 'SENSITIVE');
}
Then, in any sensitive file, you check that it's been set, and exit if it hasn't, since that means the file is being executed directly, and not by your application:
if (!defined('SENSITIVE')) {
die("This file cannot be accessed directly.");
}
Also, make sure that your include files, when publicly accessible (and really, even if not), have a proper extension, such as .php, so that the web server knows to execute them as PHP files, rather than serving them as plain text. Some people use .inc to denote include files, but if the server doesn't recognize them as being handled by PHP, your code will be publicly visible to anyone who cares to look. That's not good! To prevent this, always name your files with a .php extension. If you want to use the .inc style to show your include files, consider using .inc.php instead.

PHP & .htaccess working together

Any help on this would be greatly appreciated:
I have a website running with php on IIS6 IIS7. I am protecting all the .php files by starting a session. The .php pages can only be accessed if the session is started by logging in through the login.php page
All my .php files are in the following directory (using as example):
home/dir
Is it possible to use php and .htaccess to protect all files in the following directory:
home/dir/files
The files in this directory are word files, pdf's and other files types.
Once the user has logged in through login.php I don't want them to have to retype their username and password when trying to access home/dir/files
I hope that I made sense. Thank you.
In general, a good way to do this is to have the static files outside your website directory structure but still somewhere that the web server has permissions to access them. Then, since you're using PHP anyway, when a user requests a document, they would really be requesting a PHP page that checks the user's permissions then, if the user has adequate permissions, serves the file.
.htaccess are generally associated with Apache, not IIS, but see Is there a file-based equivalent to .htaccess in IIS6?
That said, perhaps you could put your files directory out of harms way and put it somewhere outside the document root. Then you can control download of each file through a PHP script which checks the authentication details.

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