Permissions decide who is allowed to read, write and execute each file. Get them wrong in one direction and your site breaks; wrong in the other and you have handed an attacker a way in.
The safe defaults on our servers:
- Folders - 755. You can write, everyone else can read and enter.
- Files - 644. You can write, everyone else can read.
- Config files - 600 where the application allows it. Only you.
Never set anything to 777. It is offered as a fix in a lot of old forum posts and it does usually make the immediate error go away, because it makes the file writable by every process on the server - including anything malicious that finds its way in. If an application genuinely cannot write where it needs to, the ownership is wrong, not the permissions, and a ticket will fix it properly in a couple of minutes.
To change permissions: File Manager, right-click the file, Change Permissions. To fix a whole tree at once, use the recursive option carefully - it applies to everything below the folder you selected.
