# Linux shells

**Task 1 (Introduction)**

Let us start this final Linux Introduction room in which we will learn about automation, package management, logging and more!

**Questions**

**Let’s proceed!**

> ***Answer**: No answer needed*

**Task 2 (Deploy your Linux machine)**

Nothing to do here either but logging in to your deployed machine using SSH.

**Questions**

**I’ve logged into the Linux Fundamentals Part 3 machine using SSH and have deployed the AttackBox successfully!**

Login by using ***ssh \<username>@\<serverip>***. In this case the username is tryhackme.

> ***Answer**: No answer needed*

**Task 3 (Terminal Text Editors)**

**Questions**

**Create a file using Nano**

> ***Answer**: No answer needed*

**Edit “task3” located in “tryhackme”’s home directory using Nano. What is the flag?**

Write ***nano task3*** to read the file.

<figure><img src="https://miro.medium.com/v2/resize:fit:875/0*lbo7EvmQzVyka-ev.png" alt="" height="446" width="700"><figcaption></figcaption></figure>

Using nano to read the task3.txt file

> ***Answer**: THM{TEXT\_EDITORS}*

**Task 4 (General Utilities)**

**Questions**

**Ensure you are connected to the deployed instance (10.10.213.251)**

> ***Answer**: No answer needed*

**Now, use Python 3’s “HTTPServer” module to start a web server in the home directory of the “tryhackme” user on the deployed instance.**

You will need to write ***python3 -m http.server*** to start a server on your deployed machine (the one you accessed with SSH).

<figure><img src="https://miro.medium.com/v2/resize:fit:875/0*kx-SSfYNu-19vh1I.png" alt="" height="237" width="700"><figcaption></figcaption></figure>

Serving the file, and downloading it from another terminal

> ***Answer**: No answer needed*

**Download the file** [**http://10.10.213.251:8000/.flag.txt**](http://10.10.213.251:8000/.flag.txt) **onto the TryHackMe AttackBox. What are the contents?**

Now that the server is running, you should be able to download the file by running a new terminal window.

In the new window write:

```
wget <serving machine ip>/.flag.txt.
```

Now you can access the file from your attacker machine without logging into it.

> ***Answer**: THM{WGET\_WEBSERVER}*

**Create and download files to further apply your learning — see how you can read the documentation on Python3’s “HTTPServer” module. Use Ctrl + C to stop the Python3 HTTPServer module once you are finished.**

> ***Answer**: No answer needed*

**Task 5 (Processes 101)**

**Questions**

**Read me!**

> ***Answer**: No answer needed*

**If we were to launch a process where the previous ID was “300”, what would the ID of this new process be?**

The PID increments for the order in which the process starts. So the answer should be 301.

> ***Answer**: 301*

**If we wanted to cleanly kill a process, what signal would we send it?**

The answer is SIGTERM. If you want to avoid cleaning up you can use SIGKILL.

> ***Answer**: SIGTERM*

**Locate the process that is running on the deployed instance (10.10.213.251). What flag is given?**

Enter ***ps aux*** to list the current running services of all users. If you look carefully you can find a key:

<figure><img src="https://miro.medium.com/v2/resize:fit:875/0*DzFIS7MCtPeBVUbQ.png" alt="" height="59" width="700"><figcaption></figcaption></figure>

Looking throught the ps aux output

> ***Answer**: THM{PROCESSES}*

**What command would we use to stop the service “myservice”?**

> ***Answer**: systemctl stop myservice*

**What command would we use to start the same service on the boot-up of the system?**

> ***Answer**: systemctl enable myservice*

**What command would we use to bring a previously backgrounded process back to the foreground?**

> ***Answer**: fg*

**Task 6 (Maintaining Your System: Automation)**

**Questions**

**Ensure you are connected to the deployed instance and look at the running crontabs.**

> ***Answer**: No answer needed*

**When will the crontab on the deployed instance (10.10.213.251) run?**

To figure this out simply write ***crontab -e*** in the terminal.

<figure><img src="https://miro.medium.com/v2/resize:fit:875/0*-ABgLrBKLo_uOfq8.png" alt="" height="298" width="700"><figcaption></figcaption></figure>

The crontab on the deployed instance

You can find the command in the bottom of the file. It runs on a interval specified by a special command: @reboot. Which means that it runs verything the system reboots.

> ***Answer**: @reboot*

**Task 7 ( Maintaining Your System: Package Management)**

**Questions**

Since TryHackMe instances do not have an internet connection…this task only requires you to read through the material.

> ***Answer**: No answer needed*

**Task 8 ( Maintaining Your System: Logs)**

Log files are located in the /var/log directory and contain logging information for applications and services running on your system.

**Questions**

**Look for the apache2 logs on the deployable Linux machine**

The apache2 logs are found at */var/log/apache2*.

<figure><img src="https://miro.medium.com/v2/resize:fit:875/0*EzMrCP9fXJDiLVcO.png" alt="" height="114" width="700"><figcaption></figcaption></figure>

Looking for the apache2 log file

> ***Answer**: No answer needed*

**What is the IP address of the user who visited the site?**

Access the access log by opening access.log.1 with cat.

<figure><img src="https://miro.medium.com/v2/resize:fit:875/0*Xuz1HG9fJaT2fu3c.png" alt="" height="46" width="700"><figcaption></figcaption></figure>

Reading the access.log.1 file

The answer is right there on the second line.

> ***Answer**: 10.9.232.111*

**What file did they access?**

Look at the screenshot above. They have accessed the file catsanddogs.jpg.

> ***Answer**: catsanddogs.jpg*

**Task 9 (Conclusion)**

**Questions**

**Terminate the machine deployed in this room from task 2.**

> ***Answer**: No answer needed*

**Continue your learning in other Linux-dedicated rooms**

> ***Answer**: No answer needed*


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