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Linux Fundamentals Part 2

Room information

Type: Walkthrough
Difficulty: Info
Tags: Linux
Meta Tags: Walkthrough, Walk-through, Write-up, Writeup
Subscription type: Premium
Description:
Continue your learning Linux journey with part two. You will be learning how to log in to a 
Linux machine using SSH, how to advance your commands, file system interaction.

Room link: https://tryhackme.com/room/linuxfundamentalspart2

Solution

Task 2 - Accessing Your Linux Machine Using SSH (Deploy)

I've logged into the Linux Fundamentals Part 2 machine using SSH

Login to the machine using ssh with the credentials tryhackme:tryhackme

┌──(kali㉿kali)-[/mnt/…/TryHackMe/Walkthroughs/Info/Linux_Fundamentals_Part_1-3]
└─$ ssh tryhackme@10.10.248.104
The authenticity of host '10.10.248.104 (10.10.248.104)' can't be established.
ED25519 key fingerprint is SHA256:p5icoIi8kJsmDO+nZgedjYvBWn88Lgb5VZ7nj7CaFys.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '10.10.248.104' (ED25519) to the list of known hosts.
tryhackme@10.10.248.104's password: 
Welcome to Ubuntu 20.04.6 LTS (GNU/Linux 5.15.0-1075-aws x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/pro

 System information as of Mon Feb  3 19:38:26 UTC 2025

  System load:  0.37              Processes:             114
  Usage of /:   28.3% of 9.62GB   Users logged in:       0
  Memory usage: 5%                IPv4 address for ens5: 10.10.16.227
  Swap usage:   0%


Expanded Security Maintenance for Applications is not enabled.

0 updates can be applied immediately.

Enable ESM Apps to receive additional future security updates.
See https://ubuntu.com/esm or run: sudo pro status


The list of available updates is more than a week old.
To check for new updates run: sudo apt update


The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

tryhackme@linux2:~$

Task 3 - Introduction to Flags and Switches

Useful commands:

  • man

Explore the manual page of the ls command

The result of man ls is

LS(1)                                                                                User Commands                                                                                LS(1)

NAME
       ls - list directory contents

SYNOPSIS
       ls [OPTION]... [FILE]...

DESCRIPTION
       List information about the FILEs (the current directory by default).  Sort entries alphabetically if none of -cftuvSUX nor --sort is specified.

       Mandatory arguments to long options are mandatory for short options too.

       -a, --all
              do not ignore entries starting with .

       -A, --almost-all
              do not list implied . and ..

       --author
              with -l, print the author of each file

       -b, --escape
              print C-style escapes for nongraphic characters
<---snip--->

What directional arrow key would we use to navigate down the manual page?

Answer: down

What flag would we use to display the output in a "human-readable" way?

<---snip--->
       -G, --no-group
              in a long listing, don't print group names

       -h, --human-readable
              with -l and -s, print sizes like 1K 234M 2G etc.

       --si   likewise, but use powers of 1000 not 1024

       -H, --dereference-command-line
              follow symbolic links listed on the command line

<---snip--->

Answer: -h

Task 4 - Filesystem Interaction Continued

Useful commands:

  • cp
  • file
  • mkdir
  • mv
  • rm
  • touch

How would you create the file named "newnote"?

Hint: Look at the answer formatting - we're not expecting quotation marks for this

tryhackme@linux2:~$ touch newnote
tryhackme@linux2:~$

Answer: touch newnote

On the deployable machine, what is the file type of "unknown1" in "tryhackme's" home directory?

tryhackme@linux2:~$ file unknown1 
unknown1: ASCII text

Answer: ASCII text

How would we move the file "myfile" to the directory "myfolder"

tryhackme@linux2:~$ ls
important  myfile  myfolder  newnote  unknown1
tryhackme@linux2:~$ mv myfile myfolder/
tryhackme@linux2:~$ ls
important  myfolder  newnote  unknown1

Answer: mv myfile myfolder

What are the contents of this file?

tryhackme@linux2:~$ cat myfolder/myfile 
THM{FILESYSTEM}

Answer: THM{FILESYSTEM}

Task 5 - Permissions 101

Useful commands:

  • su

On the deployable machine, who is the owner of "important"?

tryhackme@linux2:~$ ls -l important 
-rw-r--r-- 1 user2 user2 14 May  5  2021 important

Answer: user2

What would the command be to switch to the user "user2"?

Note: The password is user2

tryhackme@linux2:~$ su user2
Password: 
user2@linux2:/home/tryhackme$

Answer: su user2

Output the contents of "important", what is the flag?

user2@linux2:/home/tryhackme$ cat important 
THM{SU_USER2}

Answer: THM{SU_USER2}

Task 6 - Common Directories

Common directories:

  • /etc, short for etcetera, contains configuration and other system files
  • /var, short for variable data, contains data from services and applications
  • /root, home folder for the root user
  • /tmp, short for temporary, used to store data that is only needed temporarily

What is the directory path that would we expect logs to be stored in?

Answer: /var/log

What root directory is similar to how RAM on a computer works?

Hint: The contents of this root directory do not persist after reboot

Answer: /tmp

Name the home directory of the root user

Answer: /root

For additional information, please see the references below.

References