This module will expose you to Linux permissions, which is one of the most important parts of your journey going ahead, and mediates the access to files across different users.
In Linux, files have different permissions or file modes.
You can check out the permissions of a file or directory using ls -l.
Let's make some files and look at their permissions:
hacker@dojo:~$ mkdir pwn_directory
hacker@dojo:~$ touch college_file
hacker@dojo:~$ ls -l
total 4
-rw-r--r-- 1 hacker hacker 0 May 22 13:42 college_file
drwxr-xr-x 2 hacker hacker 4096 May 22 13:42 pwn_directory
hacker@dojo:~$
Lots of information there, and we'll learn about a lot of it in this module! For now, let's look at the output above at a high level:
The first character of each line represents the file type.
In pwn_directory's case, the d indicates that it's a directory, and in college_file's case, the - represents that it's a normal file.
There are other types as well, and you will encounter some of them later in your pwn.college journey.
The next nine characters are the actual access permissions of the file or directory, split into 3 characters denoting the permissions that the user who owns the file (termed the "owner") has to the file, 3 characters denoting the permissions that the group that owns the file (termed the "group") has to the file, and 3 characters denoting the permissions that all other access (e.g., by other users and other groups) has to the file. We will learn all about these later in the module.
There are two columns showing the user that owns the file (in this case, user hacker) and then the group that owns the file (in this case, also group hacker).
You'll mess around with that here!
In this module, you will practice perceiving permissions. Let's get started!