Submission : Assignment - 1

Ishika/assignment_1/FinalBoss/README.md

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+# File Format Converter
+
+This is a simple file format converter which allows you to convert your files between some common document formats such as:
+
+- .pdf 
+- .epub
+- .md 
+- .html
+- .txt
+- .docx
+
+### Why use this?
+
+Looking up sites and uploading files for such basic file conversions can be very time consuming, especially when one frequently needs to make these conversions. This script automates the whole process and allows us to convert a file into another format by simply putting in the file name and the format we want it in.
+
+### How to use?
+
+```bash
+./file_format_converter.sh file.extension required_format
+```
+
+### What to make sure of? 
+
+- The command-line tool used for most of the conversions - pandoc, requires LaTeX(.tex) whenever it needs to convert to pdf. Make sure to have it installed beforehand.
+_(Source: https://pandoc.org/MANUAL.html#options)_
+
+- The file must mention its original format with the file name, in the format file_name.extension.
+
+

Ishika/assignment_1/FinalBoss/file_format_converter.sh

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+#!/bin/sh
+
+input_file="$1"
+input_format="${1##*.}"
+output_format="$2"
+
+
+output_file="${input_file%.*}.$output_format"
+text_file="/tmp/tmp_conversion.txt" 
+
+
+case "${input_format}-${output_format}" in 
+txt-md|epub-md|docx-md|html-md|\
+  md-txt|html-txt|epub-txt|docx-txt|\
+  md-html|txt-html|epub-html|docx-html|\
+  md-pdf|html-pdf|txt-pdf|epub-pdf|\
+  md-docx|html-docx|docx-pdf|txt-docx|\
+  md-epub|txt-epub|html-epub)
+    pandoc "$input_file" -o "$output_file"
+    echo "Converted $input_file to $output_format"
+    ;;
+
+pdf-txt|pdf-html|pdf-md|pdf-docx|pdf-epub)
+
+    pdftotext "$input_file" "$text_file"
+    pandoc "$text_file" -o "$output_file"
+    echo "Converted $input_file to $output_format"
+    ;;
+
+*)
+
+    echo "Conversion from $input_format to $output_format not supported yet."
+    ;;
+
+esac    
+
+
+
+
+
+
+
+
+
+

Ishika/assignment_1/Git/missing-semester-lec-3/README.md

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+# Lec 6 : Version Control Systems(git)
+
+## Solutions
+
+
+2) The repo can be cloned as:
+```bash
+$ git clone https://github.com/missing-semester/missing-semester.git
+```
+
+a) Gives the version history of the given repo in graphical form.
+```bash
+$ git clone https://github.com/missing-semester/missing-semester.git
+$ cd missing-semester
+/missing-semester$ git log --all --graph --decorate
+```
+
+b) -1 only shows the last commit and -- README.md limits the log to only commits that modified README.md
+```bash
+~/missing-semester$ git log -1 -- README.md
+```
+
+c) blame looks for the modifier of only that line which contains the string "collections:". This gives us with the hash of that particular commit which we can use as an argument to the show command. It gives info about that commit, inculding the message it was commited with. 
+```bash
+~/missing-semester$ git blame _config.yml | grep "collections:"
+~/missing-semester$ git show a88b4eac
+```
+
+3)  
+```bash
+ishika@LAPTOP-0EUE93V4:~$ git init demo
+ishika@LAPTOP-0EUE93V4:~$ cd demo
+ishika@LAPTOP-0EUE93V4:~/demo$ touch secret_file
+ishika@LAPTOP-0EUE93V4:~/demo$ git add secret_file
+ishika@LAPTOP-0EUE93V4:~/demo$ git commit -m "added the secret file, uh oh!"
+[master (root-commit) ee60ad4] added the secret file, uh oh
+ 1 file changed, 0 insertions(+), 0 deletions(-)
+ create mode 100644 secret
+_file
+ishika@LAPTOP-0EUE93V4:~/demo$ git rm secret_file
+rm 'secret_file'
+ishika@LAPTOP-0EUE93V4:~/demo$ git commit -m "deleted the secret file, sigh..."
+[master e18c37f] deleted the secret file, sigh
+ 1 file changed, 0 insertions(+), 0 deletions(-)
+ delete mode 100644 secret
+_file
+ishika@LAPTOP-0EUE93V4:~/demo$ git log
+commit e18c37f3222d12c92b78438f755137625b9b7123 (HEAD -> master)
+Author: ishika <[email protected]>
+Date:   Tue Jun 3 17:15:01 2025 +0000
+
+    deleted the secret file, sigh
+
+commit ee60ad485f2e65227e1eb3e4d39ea545b617f582
+Author: ishika <[email protected]>
+Date:   Tue Jun 3 17:14:06 2025 +0000
+
+    added the secret file, uh oh
+```    
+As we can see, the commit still shows up when we uploaded that file. That means anyone with the git repo can access the contents of those files by reverting back to the state when the commit was made using checkout.
+
+To resolve this and remove our sensitive files, we use git-filter-repo.
+
+

Ishika/assignment_1/Shell/bandit-wargame/README.md

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+# Bandit : OverTheWire 
+
+## Solutions Lvl 0 - 15
+
+Note: I had already done all these levels earlier so this time around, I tried to implement some of the commands and tricks which were taught in the missing semester lecture and assignments.
+
+0) We are using ssh command which allows us to securely access remote computers over a network. Here we are using it to log into another computer using the info provided.
+```bash
+$ ssh -p 2220 [email protected]
+```
+
+1) cat reads the contents of a file. ~ denotes home directory. 
+```bash
+$ cat ~/readme
+```
+
+2) 
+```bash
+$ cat ~/-
+```
+
+3) For filenames with spaces, we can simply put them under quotation marks, so the shell does not consider each word from the file name as a separate argument.
+```bash
+$ cat "spaces in this filename"
+```
+
+4) For hidden files, -l flag can be used along with the ls command to list them along with the other files.
+```bash
+$ ls
+inhere
+$ ls -a inhere
+.  ..  ...Hiding-From-You
+$ cat inhere/...Hiding-From-You
+```
+
+5) The file command with ./* gives the type for all the files stored in the current directory.
+-file07 is the only one in human-readable format.
+```bash
+bandit4@bandit:~$ ls
+inhere
+bandit4@bandit:~$ cd inhere
+bandit4@bandit:~/inhere$ ls
+-file00  -file02  -file04  -file06  -file08
+-file01  -file03  -file05  -file07  -file09
+bandit4@bandit:~/inhere$ file ./*
+./-file00: PGP Secret Sub-key -
+./-file01: data
+./-file02: data
+./-file03: data
+./-file04: data
+./-file05: data
+./-file06: data
+./-file07: ASCII text
+./-file08: data
+./-file09: data
+bandit4@bandit:~/inhere$ cat ./-file07
+```
+6) Here we are using find to get all the files satiifying the file type and size conditions and redirecting this into xargs using piping, which will use all the files we find and use the ls command in the long list format to check if the file is executable or not.
+```bash
+bandit5@bandit:~$ find . -type f -size 1033c | xargs ls -l
+-rw-r----- 1 root bandit5 1033 Apr 10 14:23 ./inhere/maybehere07/.file2
+bandit5@bandit:~$ cat ./inhere/maybehere07/.file2
+```
+
+7) Since the file is somewhere on the server, we have to search the entire filesystem. In this process, we will find lots of files we are not permitted to open but will unnecessarily flood our terminal. To prevent this we redirected the STDERR stream to null. 
+```bash
+bandit6@bandit:~$ find / -user bandit7 -group bandit6 -size 33c 2>/dev/null
+/var/lib/dpkg/info/bandit7.password
+bandit6@bandit:~$ cat /var/lib/dpkg/info/bandit7.password
+```
+
+8) grep looks of all the lines containing the word "millionth" in the file data.txt and shows them on our terminal. 
+```bash
+bandit7@bandit:~$ ls
+data.txt
+bandit7@bandit:~$ grep "millionth" data.txt
+```
+
+9) 'sort' command as the name suggests sorts the lines of a text either alphabetically or numerically. 'uniq' removes duplicate adjacent lines and is generally used along with 'sort'. The -c flag counts the number of times a line occurs.   
+```bash
+bandit8@bandit:~$ sort data.txt | uniq -c
+```
+
+10) 'strings' command only shows human-readable lines from a text file.     
+```bash 
+bandit9@bandit:~$ strings data.txt ; grep "="
+```
+
+11) -d flag decodes the data in base64 present in the file. 
+```bash
+bandit10@bandit:~$ base64 -d data.txt
+```
+
+12) Here, we are taking the text from file data.txt and piping it into the 'tr' command, which translates the characters from a rot13 script to a normal script. 
+```bash
+bandit11@bandit:~$ cat data.txt | tr '[a-zA-Z]' '[n-za-mN-ZA-M]'
+```
+
+13) I gave the temporary directory a hard to guess name by using base64 encoding. Then I moved into that directory and copied the data.txt file there. This helped in keeping the home directory clean as there was a lot of decompressing and we could experiment here however we wanted.I also had to rename the files everytime I wanted to decompress to show the extension of the type of compression because the commands were not seeing them as valid files without proper extensions. 
+```bash 
+bandit12@bandit:~$ mktemp -d "/tmp/$(echo -n 'hard_to_guess' | base64).XXXXXX"
+/tmp/aGFyZF90b19ndWVzcw==.LUb4ip
+bandit12@bandit:/$ tmpdir="/tmp/aGFyZF90b19ndWVzcw==.LUb4ip"
+bandit12@bandit:~$ cp data.txt $tmpdir
+bandit12@bandit:/$ cd $tmpdir
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ mv data.txt hexdump.txt
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ xxd -r hexdump.txt > decoded
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file decoded
+decoded: gzip compressed data, was "data2.bin", last modified: Thu Apr 10 14:22:57 2025, max compression, from Unix, original size modulo 2^32 585
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ mv decoded decoded.gz
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ gzip -d decoded.gz
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ ls -la
+total 9988
+drwx------    2 bandit12 bandit12     4096 Jun  3 07:26 .
+drwxrwx-wt 2118 root     root     10211328 Jun  3 07:26 ..
+-rw-rw-r--    1 bandit12 bandit12      585 Jun  3 07:24 decoded
+-rw-r-----    1 bandit12 bandit12     2646 Jun  3 06:59 hexdump.txt
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file decoded
+decoded: bzip2 compressed data, block size = 900k
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ mv decoded decoded.bz2
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ bzip2 -d decoded.bz
+bzip2: Can't open input file decoded.bz: No such file or directory.
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ bzip2 -d decoded.bz2
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ ls -l
+total 8
+-rw-rw-r-- 1 bandit12 bandit12  443 Jun  3 07:24 decoded
+-rw-r----- 1 bandit12 bandit12 2646 Jun  3 06:59 hexdump.txt
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file decoded
+decoded: gzip compressed data, was "data4.bin", last modified: Thu Apr 10 14:22:57 2025, max compression, from Unix, original size modulo 2^32 20480
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ mv decoded decoded.gz
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ gzip -d decoded.gz
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file decoded
+decoded: POSIX tar archive (GNU)
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ mv decoded decoded.tar
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ tar -xf decoded.tar
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file decoded
+decoded: cannot open `decoded' (No such file or directory)
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ ls -l
+total 36
+-rw-r--r-- 1 bandit12 bandit12 10240 Apr 10 14:22 data5.bin
+-rw-rw-r-- 1 bandit12 bandit12 20480 Jun  3 07:24 decoded.tar
+-rw-r----- 1 bandit12 bandit12  2646 Jun  3 06:59 hexdump.txt
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file data5.bin
+data5.bin: POSIX tar archive (GNU)
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ tar -xf data5.bin
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ ls -l
+total 40
+-rw-r--r-- 1 bandit12 bandit12 10240 Apr 10 14:22 data5.bin
+-rw-r--r-- 1 bandit12 bandit12   222 Apr 10 14:22 data6.bin
+-rw-rw-r-- 1 bandit12 bandit12 20480 Jun  3 07:24 decoded.tar
+-rw-r----- 1 bandit12 bandit12  2646 Jun  3 06:59 hexdump.txt
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file data6.bin
+data6.bin: bzip2 compressed data, block size = 900k
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ mv data6.bin data6.bz2
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ bzip2 -d data6.bz2
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ ls
+data5.bin  data6  data8.bin  decoded.tar  hexdump.txt
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file data6
+data6: POSIX tar archive (GNU)
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ mv data8.bin data8.gz
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ gzip -d data8.gz
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ ls
+data5.bin  data6  data8  decoded.tar  hexdump.txt
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ file data8
+data8: ASCII text
+bandit12@bandit:/tmp/aGFyZF90b19ndWVzcw==.LUb4ip$ cat data8
+```
+
+14) -i flag stands for identity file which allows us to tell ssh which key to use for authentication.   
+```bash
+bandit13@bandit:~$ ls
+sshkey.private
+bandit13@bandit:~$ ssh -i sshkey.private -p 2220  bandit14@localhost
+bandit14@bandit:~$ cat /etc/bandit_pass/bandit14
+```
+
+15) nc connects us to a service on port 30000, allowing us to send and recieve passwords.
+```bash
+bandit14@bandit:~$ nc localhost 30000
+```
+
+