Linux

Joachim Desroches

BIG FAT WARNING
Craft v.s. Science

1. Linux: About and Philosophy
2. Shell
3. Asymmetric Cryptography
4. SSH and PGP
5. Git
6. Practical tools

1. Linux

kernel

# Linux is actually only the kernel, and needs a bunch of userland utilities
# to be of any use. Usually though, when we say linux, we mean the whole OS.

operating system

# Additionally to interacting with the hardware, it comes with the usual
# facilities we expect of an OS: compiler, user management, logging...

(em)power users

# General purpose, but of philosophy aimed at power users. Know what you are
# doing, think before you type, read the docs.

files

# Most powerful concept is that everything is a file. Indexed in the FSH, and
# can be accessed and manipulated that way. Example: disk, serial port.
# config!!

distributions

# Names like ubuntu, Alpine, Debian are distros. Usually represent a package
# manager and a usage philosophy.

2. Shell

# -> GNUGEN's presentation

3. Asymmetric Cryptography

secret + key > encrypted
encrypted - key > secret

share key

public key
private key

secret + public key > encrypted
encrypted - public key > garbage

encrypted - private key > secret

RSA, ECDSA

signing

secret + private key > signature
signature - public key > valid!

5. SSH and PGP

# Main crypto usage in our tooling

PGP: Pretty Good Privacy
GPG: GNU Privacy Guard

# We'll go into GPG if we have time and interest, for now let us stay on SSH.

SSH: Secure SHell

remote access

authentication keys

private & public SSH keys

# Give the server your public, and show you can decrypt the challenge

some policy

# Secrets are important! Don't let them be stolen

password-protected accounts
encrypted hard drives

# I'd say that's good enough for us for now. More would take too much
# resources to enforce. Ideally, password-protect with something in your head
# or your password manager.

5. Git

# -> GNUGEN's presentation

6. Practical tools

PuTTY, WSL - SSH for windows

gitforwindows.org