OverTheWire's Bandit: A Hands-On Guide to Linux Commands and Security Fundamentals - Part 1 (Level 0–10)

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Introduction

Welcome to my walkthrough of the Bandit game from OverTheWire! If you’re like me, you’re probably on a quest to level up your Linux skills while having some fun in the process. Bandit is a fantastic starting point for anyone looking to get their hands dirty with command-line basics and security fundamentals.

Bandit Level 0

Level Goal

The goal of this level is for you to log into the game using SSH. The host to which you need to connect is bandit.labs.overthewire.org, on port 2220. The username is bandit0 and the password is bandit0. Once logged in, go to the Level 1 page to find out how to beat Level 1.

Secure Shell (SSH) protocol is a method for securely sending commands to a computer over an unsecured network. SSH uses cryptography to authenticate and encrypt connections between devices. SSH also allows for tunneling, or port forwarding, which is when data packets are able to cross networks that they would not otherwise be able to cross. SSH is often used for controlling servers remotely, for managing infrastructure, and for transferring files.

ssh bandit0@bandit.labs.overthewire.org -p 2220

• bandit0@bandit.labs.overthewire.org specifies the username and host.

• -p 2220 specifies the port number (2220 in this case, instead of the default 22).

Helpful Reading Material

• Secure Shell (SSH) on Wikipedia

• How to use SSH on wikiHow

• SSH Command Cheat Sheet

Bandit Level 0 → Level 1

Level Goal

The password for the next level is stored in a file called readme located in the home directory. Use this password to log into bandit1 using SSH. Whenever you find a password for a level, use SSH (on port 2220) to log into that level and continue the game.

TIP: Create a file for notes and passwords on your local machine! Passwords for levels are not saved automatically. If you do not save them yourself, you will need to start over from bandit0.

Passwords also occassionally change. It is recommended to take notes on how to solve each challenge. As levels get more challenging, detailed notes are useful to return to where you left off, reference for later problems, or help others after you’ve completed the challenge.

Bandit Level 1 → Level 2

Level Goal

The password for the next level is stored in a file called — located in the home directory

Helpful Reading Material

• Google Search for “dashed filename”

• Advanced Bash-scripting Guide — Chapter 3 — Special Characters

Bandit Level 2 → Level 3

Level Goal

The password for the next level is stored in a file called spaces in this filename located in the home directory

Helpful Reading Material

• Google Search for “spaces in filename”

Bandit Level 3 → Level 4

Level Goal

The password for the next level is stored in a hidden file in the inhere directory.

Bandit Level 4 → Level 5

Level Goal

The password for the next level is stored in the only human-readable file in the inhere directory. Tip: if your terminal is messed up, try the “reset” command.

Bandit Level 5 → Level 6

Level Goal

The password for the next level is stored in a file somewhere under the inhere directory and has all of the following properties:

• human-readable

• 1033 bytes in size

• not executable

Explanation:

• . indicates the current directory (inhere in this case).

• -type f limits the search to files.

• -size 1033c looks for files that are exactly 1033 bytes (c stands for bytes).

• ! -executable excludes executable files.

Bandit Level 6 → Level 7

Level Goal

The password for the next level is stored somewhere on the server and has all of the following properties:

• owned by user bandit7

• owned by group bandit6

• 33 bytes in size

Explanation:

• / starts the search from the root directory.

• -user bandit7 limits the search to files owned by the user bandit7.

• -group bandit6 limits the search to files owned by the group bandit6.

• -size 33c limits the search to files that are exactly 33 bytes (c stands for bytes).

• 2>/dev/null redirects error messages (like "Permission denied") to /dev/null so they don't clutter your output.

Bandit Level 7 → Level 8

Level Goal

The password for the next level is stored in the file data.txt next to the word millionth

Bandit Level 8 → Level 9

Level Goal

The password for the next level is stored in the file data.txt and is the only line of text that occurs only once

Helpful Reading Material

• Piping and Redirection

Bandit Level 9 → Level 10

Level Goal

The password for the next level is stored in the file data.txt in one of the few human-readable strings, preceded by several ‘=’ characters.

Bandit Level 10 → Level 11

Level Goal

The password for the next level is stored in the file data.txt, which contains base64 encoded data

Helpful Reading Material

• Base64 on Wikipedia

Commands you may need to solve this level

Here’s a breakdown of the commands used from Level 0 to Level 11 in OverTheWire’s Bandit game, along with examples on how to use them:

1. ssh (Secure Shell)

Usage: SSH is used to remotely log into the Bandit server.

Example: ssh bandit0@bandit.labs.overthewire.org -p 2220

• bandit0@bandit.labs.overthewire.org: Username and host.

• -p 2220: Specifies the port (2220 instead of the default 22).

2. ls (List Directory Contents)

Usage: Lists files and directories in the current location.

Example:

• ls: Lists all visible files in the directory.

• ls -a: Lists all files, including hidden ones (starting with .).

• ls -l: Provides detailed information such as file permissions, owner, and size.

3. cd (Change Directory)

Usage: Navigates between directories.

Example:

• cd inhere: Moves into the inhere directory.

• cd ..: Moves back to the parent directory.

4. cat (Concatenate and Display Files)

Usage: Displays the content of a file.

Example:

• cat readme: Displays the contents of the readme file.

• cat -n filename: Displays the content with line numbers.

5. file (Determine File Type)

Usage: Describes the type of a file.

Example:

• file readme: Identifies what type of data the file readme contains (e.g., text, binary).

6. du (Disk Usage)

Usage: Shows the disk usage of files and directories.

Example:

• du -h: Shows the sizes in human-readable format (e.g., KB, MB).

• du -sh *: Displays a summary of the size of each file in the current directory.

7. find (Search for Files and Directories)

Usage: Locates files in a directory hierarchy.

Example:

• find . -name readme: Searches for the file named readme in the current directory.

• find / -user bandit7 -group bandit6 -size 33c: Searches for a file based on specific properties like owner, group, and size.

8. grep (Search Inside Files)

Usage: Searches for patterns within files.

Example:

• grep millionth data.txt: Finds the line containing "millionth" in data.txt.

• grep '^=' data.txt: Finds lines starting with the = character.

9. sort (Sort Lines of Text Files)

Usage: Sorts lines of a text file.

Example:

• sort data.txt: Sorts the lines in data.txt alphabetically.

• sort -n data.txt: Sorts the file numerically.

10. uniq (Report or Omit Repeated Lines)

Usage: Removes or reports repeated lines in a file.

Example:

• uniq data.txt: Removes adjacent duplicate lines.

• sort data.txt | uniq -u: Finds unique lines after sorting.

11. strings (Find Printable Strings in Binary Files)

Usage: Extracts printable text from binary files.

Example:

• strings data.txt: Displays human-readable strings in the data.txt file.

12. base64 (Base64 Encoding/Decoding)

Usage: Encodes or decodes base64 data.

Example:

• base64 -d data.txt: Decodes base64-encoded data in data.txt.

• echo "password" | base64: Encodes the word "password" in base64.

13. tr (Translate or Delete Characters)

Usage: Translates or deletes characters from input.

Example:

• cat data.txt | tr 'a-z' 'A-Z': Converts lowercase letters to uppercase in data.txt.

• cat data.txt | tr -d '=': Deletes the = characters from the output.

14. tar (Tape Archive)

Usage: Archives multiple files into a single file and extracts them.

Example:

• tar -xf archive.tar: Extracts the contents of archive.tar.

• tar -czf archive.tar.gz directory: Compresses a directory into a .tar.gz file.

15. gzip (Compression Utility)

Usage: Compresses files using the GNU zip algorithm.

Example:

• gzip file.txt: Compresses file.txt to file.txt.gz.

• gzip -d file.txt.gz: Decompresses the file.

16. bzip2 (File Compression)

Usage: Compresses files using a higher compression ratio than gzip.

Example:

• bzip2 file.txt: Compresses file.txt into file.txt.bz2.

• bzip2 -d file.txt.bz2: Decompresses the file.

17. xxd (Hex Dump Tool)

Usage: Creates a hex dump of a file.

Example:

• xxd data.txt: Converts the file data.txt to a hexadecimal representation.

• xxd -r data.hex: Converts the hex dump back into its original format.

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Thanks for reading and stay tuned!!!