Warning: This post contains a solution!
Only continue if:
1.) you want to see a possible alternative solution or
2.) you are stuck and need a hint!
Connect to the server using the following credentials:
Level Goal is:
The password for the next level is stored in the file data.txt and is the only line of text that occurs only once
With this information in mind, we can search for a unique line in the file. We can use the uniq command to do that.
bandit8@bandit:~$ man uniq UNIQ(1) User Commands UNIQ(1) NAME uniq - report or omit repeated lines SYNOPSIS uniq [OPTION]... [INPUT [OUTPUT]] DESCRIPTION Filter adjacent matching lines from INPUT (or standard input), writing to OUTPUT (or standard output). With no options, matching lines are merged to the first occurrence. [...] Note: 'uniq' does not detect repeated lines unless they are adjacent. You may want to sort the input first, or use 'sort -u' without 'uniq'. Also, comparisons honor the rules specified by 'LC_COLLATE'. [...]
As described under 'Note:', we first have to sort the list.
So, just combine sort and uniq:
bandit8@bandit:~$ sort data.txt | uniq -u UsvVyFSfZZWbi6wgC7dAFyFuR6jQQUhR