Selective permission to write in the directory.

[Kurda Yon]

I want to create a publicly accessible php page which will generate
images (with the GD library) and store them in some directory. For
this I have to change the permission of directory (it has to be
writable for everybody). However, as far as I understand, this will
allow everybody to put in the directory whatever files. I would like
that only my php program has permission to write to the directory. Is
there any possibility to do that?

[dourdoun]

You are reffering to other users with access (ssh, ftp, etc...) on the
same box.
Web users have no direct access to this folder (only through your
script which you can control)

Assuming you are on a unix machine using apache httpd:

You can give write access only to the user apache runs as.

Set apache user as owner:
chown -R apache.apache /path/to/writable/dir

Set permissions:
chmod -R 755 /path/to/writable/dir

Note: depending on your server's version and setup associated user
might be 'apache', 'nobody' or something else. If you are on a shared
hosting environment apache might be using your own user's permissions.

Hope this helps.

On Jul 29, 3:22 pm, Kurda Yon <[e-mail]:

I want to create a publicly accessible php page which will generate
images (with the GD library) and store them in some directory. For
this I have to change the permission of directory (it has to be
writable for everybody). However, as far as I understand, this will
allow everybody to put in the directory whatever files. I would like
that only my php program has permission to write to the directory. Is
there any possibility to do that?

[Jerry Stuckle]

Kurda Yon wrote:

I want to create a publicly accessible php page which will generate
images (with the GD library) and store them in some directory. For
this I have to change the permission of directory (it has to be
writable for everybody). However, as far as I understand, this will
allow everybody to put in the directory whatever files. I would like
that only my php program has permission to write to the directory. Is
there any possibility to do that?

Your PHP script will run under the Web Server's user id, and should
limit access to that id. It doesn't matter who is accessing your web
page. Other users should not have direct access (i.e. ftp) to the
directory.

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attglobal.net
==================

[Kurda Yon]

I am not sure that I understood correctly. Is the logic as following?
All those, and only those, users which communicate with my server via
my php-script are seen by the server as 'nobody'. So, in the case if
ONLY 'nobody' has permission to write and execute the directory, the
content of the directory can be changed ONLY via my php-script. Do I
correctly understood?

[bxd]

On Jul 29, 5:30 pm, Kurda Yon <[e-mail]:

I am not sure that I understood correctly. Is the logic as following?
All those, and only those, users which communicate with my server via
my php-script are seen by the server as 'nobody'.

Something like that.
To put it another way, your webserver has access to the file system as
'nobody' (or whatever stands for your configuration).
Web users send requests to your webserver which handles them
appropriately (reads/writes files).

So, in the case if
ONLY 'nobody' has permission to write and execute the directory, the
content of the directory can be changed ONLY via my php-script. Do I
correctly understood?

Correct.

[gosha bine]

Kurda Yon wrote:

I am not sure that I understood correctly. Is the logic as following?
All those, and only those, users which communicate with my server via
my php-script are seen by the server as 'nobody'. So, in the case if
ONLY 'nobody' has permission to write and execute the directory, the
content of the directory can be changed ONLY via my php-script. Do I
correctly understood?

No ;)

There is a common confusion between "users" of your website and "users"
on your unix server. Users of the website are the people who visit it,
like me and you, users on the server are people and programs listed in
the server's /etc/passwd file. Website visitors have no rights on the
server, because they are not listed as "users" there. The permission
question is only relevant when we're talking about server users, not
about website visitors.
Most php installations are configured in the way that php scripts run
under the webserver user ("nobody", "www" or similar). On a shared
hosting, that means that the files you create can be also accessed by
everyone else hosted on the same server, because his scripts and yours
have same permissions.
php tries to solve this problem with notorious "safe mode", though it's
easy to fool around. You should consider dedicated hosting if security
is a concern.

--
gosha bine

extended php parser ~ http://code.google.com/p/pihipi
blok ~ http://www.tagarga.com/blok