Linux Fundamentals - Part 1
Task 1 - Intro
Getting logged into the box once it's started up.
Task 2 - Methodology
Nothing to do here.
Task 3 - Basic Command Execution
Simple command testing, within your VM. Start by doing echo with some text after it to write out to your terminal.
Task 4 - Manual Pages and Flags
In this section we learn about the man command. Which is often quite useful for finding the switches a command will take. The below line will open up the man page for the ssh command.
Task 4.1 - How would you output hello without a new line
Start by running:
When we review the switches, we can see that the option for -n will provide us with the output we desire, a message without a new line.
Task 5 - ls
Time to review the ls command. This command is used to list the files within a directory.
Run man ls to review the switches / options which can be used to provide and allow for additional functionality when using ls.
Task 5.1 - What outputs all entries
Review the man page for this option, which is -a.
Task 5.2 - What outputs things in a "long list" format
Review the man page, the switch is -l
When I review a directory I will often use a combination of the previous switches, ls -al, to allow for a better understanding of what files are present.
Task 6 - cat
cat - Concatenate FILE(s) to standard output.
Task 6.1 - What flag numbers all output lines
Run man cat, sift through the list of switches. We see that -n provides line numbers to the output.
Task 7 - touch
touch - Update the access and modification times of each FILE to the current time.
No tasks for this section we need to answer.
Task 8 - Running a Binary
| Relative Path | Meaning | Absolute Path | Relative Path | Running a binary with a Relative Path | Running A Binary with an Absolute Path |
|---|---|---|---|---|---|
. | Current Directory | /tmp/aa | . | ./hello | /tmp/aa/hello |
.. | Directory before the current directory | /tmp | .. | ../hello | /tmp/hello |
~ | The user's home directory | /home/<current user> | ~ | ~/hello | /home/<user/>/hello |
export <varname/>=<value/> will set that as an environment variable \
It is worth noting that not all commands support the pipe, and some that do support it require you to use - instead of input, for example cat -. So always check to see if the command does support it.
The ; operator works a lot like &&, however it does not require the first command to execute successfully. This means that you can do dkhsgffgsafgfasdgfasfghkgdsgfs; ls and you would still see the output of ls.
Task 8.1 - How would you run a binary called hello using the directory shortcut
Reviewing the table of contents posted previously in regards to relative paths we see that using . is our current directory, so using ./ will run a binary from our current path. So with this we can safely assume that using ./hello will run a binary named hello.
Task 8.2 - How would you run a binary called hello in your home directory using the shortcut ~
Refer to the previous table and we can see that ~ represents our home directory. By using ~/hello this will run the binary hello, from our home directory.
Task 8.3 - How would you run a binary called hello in the previous directory using the shortcut ..
Looking back at the table, we see that .. represents the action of moving to a directory prior to our current directory. Running ../hello will move one directory up, and run the hello binary found there.
Task 9 - Binary - Shiba1
While logged into our vulnerable system, we now need to run a binary.
Task 9.1 What's the password for Shiba2
We can run the following in order to get the password for the shiba2 account:
Task 10 - su
su allows to run commands with a substitute user and group ID.
When called without arguments, su defaults to running an interactive shell as root.
Task 10.1 - How do you specify which shell is used when you login
Run the good ol' man su command. Look through our options, we can see that -s will provide us with the specified shell instead of the default, such as /bin/sh, /bin/zsh, etc.
Task 11
Click complete, time to move on to Linux Fundamentals Part 2!