OverTheWire Bandit Level 8 → 9 tutorial!!

Login

Log in as bandit8 using the password you just obtained from Level 7 → 8.

ssh bandit8@bandit.labs.overthewire.org -p 2220
# password: dfwvzFQi4mU0wfNbFOe9RoWskMLg7eEc

Why? Each Bandit level is a separate UNIX user. To solve 8 → 9, you must be the bandit8 user.

Task

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

A little bit of Theory

• sort groups identical lines together (lexicographical order).

• uniq examines adjacent equal lines, so it works properly after sort.

  • uniq -u prints only lines that appear once.
  • uniq -c prints counts; can be combined with another sort to view frequencies.
• For speed and predictable ordering, you can use LC_ALL=C sort.

Further reading:

• sort manual
• uniq manual
• Piping and Redirection

Solution

1. Confirm the file exists

   ls -l
   

   Why? Sanity check before running heavy commands.

1. Find the line that appears exactly once

   sort data.txt | uniq -u
   # or (locale-agnostic & often faster)
   LC_ALL=C sort data.txt | uniq -u
   

   Why? sort groups duplicates; uniq -u keeps strictly-unique lines.

1. (Optional) Inspect counts to be sure

   LC_ALL=C sort data.txt | uniq -c | sort -n
   # then pick the one with count 1 (print only the line):
   LC_ALL=C sort data.txt | uniq -c | awk '$1==1{$1=""; sub(/^ /,""); print}'
   

   Why? Good when you want to verify there’s exactly one unique line.

2. Copy the password (no extra spaces/newlines).

3. Log into the next level (bandit9)

   exit
   ssh bandit9@bandit.labs.overthewire.org -p 2220
   # paste the password you just found when prompted
   

Password

This is the password shown in my run; if yours differs, copy the one from your own terminal output.

4CKMh1JI91bUIZZPXDqGanal4xvAg0JM

Troubleshooting

• Using sort -u? → That removes duplicates but still keeps one copy of repeated lines; you want lines that occur only once → use uniq -u.
• Slow sort? → Use LC_ALL=C sort to avoid locale collation overhead.
• Garbled output? → Check for weird control characters with cat -A data.txt | head.

Congrats 🎉 You sifted through a massive file and found the unique line — on to bandit9!

Thanks for reading!

Until next time — Otsumachi!! 💖☄️✨