Getting to grips with ownership
and permissions

Ruth Cheesley Virya Technologies
@RCheesley / @ViryaTech

Did you tell people you're at @JoomlaSuffolk this evening? Did you check in at Basepoint?

In an interconnected world, we need to control who can access what!

Data is everything in the digital age with vital information no longer entrusted to lock and key but being stored on computers often thousands of miles away from where they were deposited.

Controlling who can access this data whether it be your bank account or your facebook photos comes down to a simple matter of ownership, and permissions.

People often get totally baffled by these core concepts so hopefully this should make a bit of sense and help you understand how it works.

Once you 'get' this you're over a large hurdle when it comes to web design and hosting issues!

Emergency Phone Number
(share with all who know where to find it)

I might want to sharesomething with just thisgroupSome things I mightwant to share with
these groups

Some things I want to Share with everyone(the world)

Some things I mightonly want to be availableto me (owner)

Facebook

So how does it all work
'behind the scenes'?

World

(The world, the universe, and everything not in the same groupas the owner)Group

(A set of users in the same group as the owner)Owner

(owns the file)

Read (r)

Write (w)

Execute (x)

Can view the fileChmod +r / -rNumerical value = 4

Can make changes or modify the fileChmod +w / -wNumerical value = 2

Can run the file (generally applicable at command line)Chmod +x / -xNumerical value = 1

NOTE: Folders cannot be listed and files within can't be accessed if the folder does not have execute permissions

So what about 7's and 6's

All permission combinations are derived by adding these basic permissions

7 represents Read (4) + Write (2) + Execute (1)

6 represents Read (4) + Write (2)

Basic file permissions

NumberPermission

0Deny all

1Execute (x) only

2Write (w) only

3Write & Execute (2+1)

4Read only

5Read & Execute (4+1)

6Read & Write (4+2)

7Read + Write + Execute (4+2+1)

Important considerations

Write permissions are required for moving a file

You must be owner of a file/folder to change its permissions

You need read permission on a folder to show the contents

Generally permissions are tighter for 'world', less so for 'group' and least for 'owner'

So what does 755 and 644 mean?

In Joomla! Folders should be 755 and files 644 configuration.php should be 444

What does this mean?

Let's work it out!

Joomla! permissions

OwnerGroupWorld

7(Read + Write + Execute)rwx5(Read + Execute)r-x5(Read + Execute)r-x

6(Read + Write)rw-4(Read)(r--)4(Read)(r--)

What is chmod all about?

A command you can use to change the permissions on files and folders

Used in command line

Example:

chmod [options] [permissions] [item]

chmod +R 644 MyFolder

Why does this cause problems?

Generally down to poor setup by hosting providers (or simply lack of awareness)

Usually relates to how Joomla! was originally installed

Which user 'owns' the files and folders, and therefore has or doesn't have permissions

FTP username is joebloggs

Therefore OWNED by joebloggs

joebloggs is in the managers group

File and folder has permissions which restrict who can:

Read

Write

Execute

Trying to access and/or movefiles and/or folders, or listfolders will result in:

If file/folder is not available with appropriate access, 403 forbidden

If file/folder is available with appropriate access, access granted

Where it goes wrong

World

(The world, the universe, and everything not in the same groupas the owner)Group

(A set of users in the same group as the owner)Owner

(owns the file)

How to fix this

Chmod the files & folders to the correct permissions, if permission is an issue (or use Admin Tools!)

Set up the server correctly - www.virya.co.uk/joomlaserversetup

The geeky stuff

If your server runs mod_phpDocument root: 750

Directories: 755 (711 if you're paranoid only if not listed)

Files: 644

If your server runs fast-cgi, suphp or cgiDocument root: 750

Directories: 755 (711 if you're paranoid only if not listed)

HTML & Image files: 644 (444 if you're paranoid)

PHP files: 600 (400 if you're paranoid)

SOURCE: www.virya.co.uk/joomlaserversetup

A word of warning

It's very useful to have a basic understanding of ownership & permissions to help you troubleshoot, but TAKE BACKUPS!

You can completely break things by tinkering with permissions if you don't know what you're doing!

If in doubt, speak to a geek!

Thank you!

Any questions?

Ruth Cheesley@Rcheesley / @ViryaTech