L in u X ba sics for h acke rs g e t t I n g s t a r t e d w I t h

Granting Permissions
Each and every file must be allocated a particular level of permission 
for the different identities using it. The three levels of permission are as 
follows:
r
Permission to read. This grants permission only to open and view 
a file.
w
Permission to write. This allows users to view and edit a file.
x
Permission to execute. This allows users to execute a file (but not 
necessarily view or edit it).
In this way, the root user can grant users a level of permission depend-
ing on what they need the files for. When a file is created, typically the user 
who created it is the owner of the file, and the owning group is the user’s 
current group. The owner of the file can grant various access privileges to 
it. Let’s look at how to change permissions to pass ownership to individual 
users and to groups.
Granting Ownership to an Individual User
To move ownership of a file to a different user so that they have the ability 
to control permissions, we can use the 
chown
(or change owner) command:
kali >chown 
u
bob 
v
/tmp/bobsfile
Here, we give the command, the name of the user we are giving owner-
ship to, and then the location and name of the relevant file. This command 
grants the user account for Bob u ownership of bobsfile v.

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Controlling File and Directory Permissions
51
Granting Ownership to a Group
To transfer ownership of a file from one group to another, we can use the 
chgrp
(or change group) command.
Hackers are often more likely to work alone than in groups, but it’s not 
unheard of for several hackers or pentesters work together on a project, and 
in that case, using groups is necessary. For instance, you might have a group 
of pentesters and a group of security team members working on the same 
project. The pentesters in this example are the root group, meaning they 
have all permissions and access. The root group needs access to the hack-
ing tools, whereas the security folk only need access to defensive tools such 
as an intrusion detection system (IDS). Let’s say the root group downloads 
and installs a program named newIDS; the root group will need to change 
the ownership to the security group so the security group can use it at will. 
To do so, the root group would simply enter the following command:
kali >chgrp 
u