Command Line Bootstrap


#1

CRITICAL ENGINEERING

SUMMER INTENSIVES, BERLIN 2017 FOUNDATIONS

COMMAND LINE BOOTSTRAP

WITH JULIAN OLIVER AND DANJA VASILIEV

Live Notes by: Hen of StratoFyzika

Introduction:
The Linux system is ubiquitous.
used in planes, trains, automobile and now with the use Smart line devices

Interacting with servers (machines with no screen interface) requires the use of the command line
ex. Raspberry Pi

This is a fast crash course in basic command line:

Terminal

inside is the shell
user is the name you log in as @ signifies the user is working on a particular machine
: separates between the files system part, ~ is a shortcut from your home directory /home/user

First Command (present working directory)
pwd
tells us where we are

ls (list)
it is like a light that you turn on in a room

ls De (plus tab, creates a shortcut to reach) ls Desktop/

cd Desktop/

~Desktop$ pwd

touch list.txt
touch creates a file, and updates the date on the file
creates an empty file on the desktop

touch list.jpg

content is the data

cat list.txt
reflects what is in the .txt

echo “lalala” > list.txt
redirecting the text into the file

spaces are very important in the shell

echo “glah blah blah” >>list.txt
the use of two arrows tells it to not overwrite the whole file

 use the arrow keys to scroll through your history

mkdir archived
creates a file called archived
mv list.txt archived/
moves the file list.txt to that folder

cp list.txt archived/list2_backup.txt

clear
shortcut is ctrl + l
(histroy is saved but refreshed the terminal screen)

  • r
    stands for recursive (the nesting of one thing inside another)

rm
to remove files

rm -r archived
because it is a folder, you must include recursion

mkdir -p 1/2/3/4/5/6/7/8
creates folders within folders

ctrl a(beginning of the line), ctrl e (end)

cd -
takes you back between folders

cd …/

Full Path would be written
cd /home/user/Desktop?1/2/3

cd
takes you home

`/Desktop/1/2/3
tilda is a shortcut for cd

Variables
a=371.56
echo $a

echo$HOME

Linux File System:

Full path gets defined by the use of a slash at the beginning, which represents the root directory of any unix like file system (like the trunk of tree)

/

If you type ls /
You get the directory:
Bin
Boot
Dev
Ect

Home
Lib
Media
Met
proc

ls /bin/

insert file directory photo here

green files are programs

locate list.txt
goes through the files system and finds where it is

sudo updatedb
superuser
enter password

locate *.txt
locates all .txt files

find
for a specific name in a particular directorz

find requires a .
find . ~name list.txt

find . ~name *.jpg

Find /usr /share/ ~name *.wav

File
Command will tell you what kind of file it is
File /usr/share/sounds/alsa/Noise.wav

**You can use this command to check information about a file

ex.

Cp /bin/ls ~desktop/letter .txt

You can use File ~/desktop/letter.txt to check the contents of this file which is in fact a binary file

If you check it using File and it reflects the contents of your directory, then there are files being uploaded from your computer.

What is useful about this is that you can see what is really there rather than taking ones word for it

Linux environment can Cache value to look at the Footprint of a file

Sha
Is the command

Sha256sum
You can scan the system for the id number which is unique to that file.
Can be checked to see if someone has modified a file like a .jpg, for instance

Ls - l

figlet “you have been owned!”
figlet “you have been owned!” > ls
Nano ls
Ls -la

Replaced the system binder with a script
And put it on the list

Cheatsheet, downloads, cheatsheet pdf

GNU all the tools onto of the linux kernel


Zip ~r archived_backup.zip archived_backup

working with text
to check the number of characters, lines, words

-c
-l
-w

changing instances of words from one to another
there is one to check it
and there is one to overwrite it

sed 's/more/messy/' rand.txt > messy.txt
cat messy.txt

join big chunks of data together
cat 0.txt >>rand.txt

>> is adding to a file instead of overwriting it

NANO
nano newfile.txt
at the bottom of this page there are many shortcuts
ex. Write out
ctrl + x to exit

nano newfile.txt
nano anotherfile.txt
nano anotherfile.txt

Learn VIM

Date and Time

cal

cal june 2018

date

More Commands

ubuntu/debian
repository is like an app store
commad line interfaces:

ubuntu mirrors, represented by a separate package

APT
apt-get
receive and install software

sudo apt-get update

sudo apt-cache search links
sudo apt-cache search console | grep -i music

text based software such as lynx links

sudo apt-get install lynx links
install

Links

can look at the barebones of a website
can download an image

Lynx

you can also run a website directly in the command line
press g in the program and search directly for the url

also good for viewing html files

open and esc to get to the other menu
enter a website

lynx http://www.google.com

mk dir web-dumps
cd web-dumps/
ls
wget - - help

help page opens

WGET
wget -r https://weise7.orgw
download the whole site page by page
will be a mirror on your local file system

man wget
help page

fetch remote pages/files
retrieve a url directly to your own machine

Linux is what the internet was built on

  • amazing networking stack
  • stable

Whois

who is behind spiegel.de

whois spiegel.de
looks up the contact info

ip address
host spiegel.de

geoiplookup (enter ip address)
host spektrumberlin.de

Ping
ping pong with a data packet to a remote server
ex. google"s zms server 8. 8. 8. 8
ctrl + c will end the ping


Remember the terminal hosts the shell

what about when interacting with a remote machine

on virtual machine, run:
sudo apt-get install arp-scan

sudo apt-get install net-tools

change the from NAT to bridged adapter, randomize the mac address

rerun
ifconfig

ex ip: 192.168.12.139

invoke a remote shell on another machine

SSH
sudo apt-get install openssh-server

ssh user@192.168.12.137

now when i run ifconfig
you can see you are now on that ip

ssh is used by govt, banks, encrpted
pass ssh a command (shell users), execute a command and log out again

ssh user @192.168.12.137 "ls -l Pictures
“ls-l Desktop”

You can leave a msg on your desktop if you know the ip and the password and the correct user

Copy Forward
cd Desktop
ls
mv image…jpg
scp some.jpg
some copy user@ip address:.
. represents home directory
:Desktop/
would be the desktop

Tunnel

Reverse Copy
scp user@ip address:Desktop/lala.txt .
(reverse the syntax)

mkdir hens - desktop
scp -r user@ipaddress:Desktop/* Hens-Desktop/

Can you see the differences between Copy fwd and Reverse copy?!

stealthy technique: create a space so that it would never be kept in the history " ls Desktop"

Remote Device Command
ssh into the device, pi
ssh pi@192.168.12.13

asks for password

now displays pi@raspberrypi ~ $

ls /dev/
printf (something similar to echo)

printf "\x7C\x00 Message from the net" > /dev/tty50
tells the screen to clear out and then you can print your message

exit from pi

NCAT
nc 192.168.12.13. 3333

ctrl + c to exit

Shell Scripting

combination of comands
commands logically following each other

mkdir foo; cd foo
semicolon expreses, after doing that first step, do the second step

while true; do date; sleep 1; done
this is a very simple program which requires ctrl + c to exit

nano current-time.sh
sh indicates shellscript

#! /bin/bash
bash is born again shell, default on osx

while true;
do
date
sleep 1
done

chmod +x current-time.sh
add executability to this file, so it can be run as a program
-x
is to disable a program

./
means execute this file here

./current-time.sh

the space between the do and the dont, any commands can be run.

if [ -f letter.txt ] ; then
else

mail -s “letter.txt was removed!” ^email@address