EC2 (Elastic Cloud Computing)

 

EC2 (Elastic Cloud Computing):

Amazon Elastic Compute Cloud (Amazon EC2) is a web service that provides secure, resizable compute capacity in the cloud. It is designed to allow you to obtain and configure capacity with minimal friction and to make web-scale cloud computing easier for developers.

Amazon is elastic/flexible, supports lot of OS flavours

 

 

 

Default users to login to ec2:

ec2-user

ubuntu

centos

root

admin

 

To configure password less authentication between 2 ec2 instances:

1. Login to ec2 instance and change ssh configuration file /etc/ssh/sshd_config as below

PermitRootLogin prohibit-password to  PermitRootLogin yes

      PasswordAuthentication no  to   PasswordAuthentication yes

     Then restart ssh

RHEL à service sshd restart

 Ubuntu à service ssh restart

To have password less authentication between 2 instances, master and slave:

2. Generate the keys using ssh-keygen on master
3. Copy the keys using from master to slave using

ssh-copy id -I ~/.ssh/id_rsa.pub root@slave

 

 

ec2 instances:

 

When you launch an EC2 instance, you receive a Public IP address by which that instance is reachable.

Once you stop that instance and restart the you get a new Public IP for the same instances.

 

So, Public IP gets changed every time for an instance after stop/start.

 

To overcome with this problem, we attach an Elastic IP to an Instance which doesn't change after you stop / start the instance as many times.

 

Advantage of Having Elastic IP

-> It is kind of static IP for your Instance.

-> Doesn't change after stop/start.

 

Note: If you have Elastic IP in your account and it’s not in use, then you will be charged for it.