Regions and AZ

HYD -> Region
North HYD -> AZ-1
South HYD -> AZ-2

Region has atleast 2 or many

us-east-1 -> N.Virginia -> cheapest region, new services are going to be launched here

latency -> may be high, we can't notice

6AZ, 2AZ

order server, install OS, Power connection, Network, AC, Physical security, storage, etc...

Migrate to cloud

IP enabled device...

OS -> Embedded Linux -> Bridge between user and hardware
RAM
HD
Processor

Windows vs Linux
================
User interface is heavy in windows -> slow, Linux is super speed
Linux is more secure than windows
	Low power
	Low bandwidth
	Low ram
	Long running servers
	Linux is open source -> almost free
	
Linux -> Kernel
Linus Torvalds -> Git, Linux

IBM BIOS(PC), Server(Hardware+OS) -> Unix

Hardware+Software -> Tight coupling
Dell ->

Linux -> using C language from the scratch -> Unix Principles

Kernel -> like heart and brain(Hardware interaction)
Linux is kernel

Oracle, Redhat, Debian, etc. -> distributions/flavours
99% same
1% 

Opensource -> community support
Enterprise -> support, if problem comes, they join our and resolve the issue asap

Redhat Enterprise Linux -> RHEL == centos == AWS Linux == fedora ==> RedHat family

AWS Linux 2023 -> 
Redhat image

Authentication and Firewall
===========================

1. What you know -> username and password
2. What you have -> RSA Token, Authenticators, Public key and private key etc..
3. What you are -> Retina, plam, fingerprint, etc..

ssh-keygen -f <file-name> -> it will generate two keys. public and private

git -> interact with git repos, mini linux(we can use some linux commands in windows)

pwd -> present working directory

/c/Users/siva

/c/Users/ramesh

C:\devops\daws-90s -> windows format
/c/devops/daws-90s -> linux format

cd -> change directory

Firewall -> authorised persons only will have access

inbound/ingress -> incoming traffic -> we check and allow
outbound/egress -> outgoing traffic -> usually we allow egress traffic everyone

SSH -> Secure shell -> protocol to connect Linux servers terminal access

http -> hyper text transfer protocol
https, ftp, ssh, mysql, smtp, dhcp, udp, tcp, etc...

Connection/Communication between multiple computers

https://facebook.com:443 -> facebook DB
http://facebook.com:80

0-65,535 = 65,536 ports

protocol, ip, port number, authentication

ssh facebook server -> admin access

ssh -> 22

firewall/security group -> SSH 22 allow 0.0.0.0/0 (anyone can connect)

ssh -i <private-key> ec2-user@IP-address

1. read the description of error
2. then search in google, gpt
3. put in slack
4. join qa sessions

/home/<user-name> -> ec2-user -> AWS default user

command -> understand the usage

command <options> <inputs>
-a -> single char -> short version
--all -> all information

2 types of users
1. normal user -> $
2. admin user -> #

sudo su -> super user

absolute path -> from starting
relative path -> from where you are

/c/devops/daws-90s -> absolute path
daws-90s/daws-90s

Linux commands