So what? Let's say you're in an engagement and you want to run Nmap in one window, plus run Metasploit in another one, and so on. This is where Tmux is handy, because you can work on multiple windows/sessions at the same time.
Tmux Key Bindings
In Tmux, you must use Ctrl+B to instruct it that you want to execute a Tmux action (command). In fact, the key combination Ctrl+B is the default one. You can always change the default configurations of Tmux in the configuration file. To change this behavior and assign Ctrl+A instead of Ctrl+B, then you must create the config file yourself for the first time. To get the job done, you have two options for creating a config file in Tmux. The first way is to add a user‐specific file called ~/.tmux.conf , and the second way is to add a global file (to all users) under /etc/tmux.conf . In my case (for this example), I will add the configuration file under /etc/tmux.conf (and I will add the configurations for the key bindings in it):
root@kali:/# touch /etc/tmux.conf root@kali:/# echo unbind C-b>> /etc/tmux.conf root@kali:/# echo set -g prefix C-a>> /etc/tmux.conf root@kali:/# echo bind C-a send-prefix>> /etc/tmux.conf
Tmux Session Management
In Figure 1.1, you can see that the name bash has been assigned automatically to your current session.
Window Rename
To rename the session, press Ctrl+B first (or Ctrl+A if you made the changes in the config files that we did previously). Then remove your fingers from the keyboard and press the comma (,) key on your keyboard. You should see that the prompt has changed to allow you to rename it. I will call it Window1; then press Enter after finishing the task:
(rename-window) Window1
Window Creation
At this stage, we have only one window, so let's create a second one by pressing Ctrl+B and then pressing the C key. Looking at the bottom, you'll see you have a new bash window, and Tmux has already highlighted the current tab with an asterisk (*), as shown in Figure 1.2.
Figure 1.2 New Tmux Highlighted Tab
Splitting Windows
To split the selected tab into two subwindows side by side, as shown in Figure 1.3, you must press Ctrl+B and then enter the % character on your keyboard (remember that you need to press Shift+% or else it will be considered 5 on your keyboard).
Figure 1.3 Tmux Vertical Windows Side by Side
Navigating Inside Tmux
Amazing, right? As you can see, the cursor is on the right pane (see Figure 1.3). To switch between panes (subwindows), press Ctrl+B and use the arrow keys on your keyboard (to change left, right, up, and bottom).
Next, go back to the Window1 session. To switch between windows, press Ctrl+B and then the number of the window (which is 0 according to this example), and we should be back to the first window.
Now, divide the window into two sections, one over the other, as shown in Figure 1.4. To get this done, use Ctrl+B and then the double quote (“). Remember that you need to press Shift+“ or else that key produces a single quote.
Figure 1.4 Tmux Horizontal Windows
The final tip for managing Tmux is for scrolling up and down inside a window or a pane session. In fact, you can't use your mouse to scroll up and down in a Tmux session (the mouse scrolling is for commands history). Instead, you need to press Ctrl+B and then [ on your keyboard, and after that you can use the up and down arrow keys on your keyboard to scroll. Once you're done with the scrolling, press Esc or the Q key on your keyboard to go back to the normal mode.
To close a pane or a window, just use exit like with any regular terminal window session.
Tmux Commands Reference
Table 1.1 summarizes all the Tmux commands that you learned in this section. You can use it as a reference (this is just a quick guide so you can start using Tmux; if you want to go beyond basics, check the manual reference).
Table 1.1 Tmux Keyboard Shortcuts
| DESCRIPTION | COMMAND |
|---|---|
| To rename a window | Ctrl+B+, |
| To open a new window | Ctrl+B+C |
| To split windows vertically | Ctrl+B+% |
| To split windows horizontally | Ctrl+B+" |
| To navigate subwindows | Ctrl+B+Left Arrow, Ctrl+B+Right Arrow |
| To switch between windows | Ctrl+B+[window number] |
| To scroll up | Ctrl+B+[+Up Arrow |
| To scroll down | Ctrl+B+[+Down Arrow |
| To escape the scrolling mode | Esc |
| To close a pane/window | Type exit (inside it) |
Managing Users and Groups in Kali
Understanding the commands for managing users and groups is important because you'll use the information when you learn about privilege escalation later in the book. All the commands in this chapter will help you a lot in your engagements while using Kali Linux (as an OS for your pentests).
Figure 1.5 summarizes all the commands related to users' management/security in Kali Linux.
Users Commands
Low‐privilege users must prepend commands with sudo to execute system commands (and the low‐privilege user must be in the sudo group to execute sudo ). You will be asked for your account password if you want to use the sudo command. For example,