How to create users for your EC2 Instance that can connect securely via ssh

Public and Private Keys for AWS Users

Create a normal user in AWS

sudo adduser username

How to add user in sudo group or wheel group

sudo usermod --groups sudo --append username

Allow user to run the sudo command without asking the password

root    ALL=(ALL)       ALL
username ALL=(ALL) NOPASSWD:ALL

Or you can add complete sudo or wheel group. The users under sudo or wheel group run sudo command with asking password to sudo users

%wheel ALL=(ALL) NOPASSWD:ALL
%sudo ALL=(ALL) NOPASSWD:ALL

To switch to the user directory

cd /home/username

Run the following command inside the user home directory to generate keys

ssh-keygen - b 4096 -f username -t rsa

To create the .ssh directory under user home directory

 mkdir .ssh

Give permission to the owner to read, write and execute (700) 

chmod 700 .ssh

To store public key in authorized_keys file (after exit from the username )

sudo cat username.pub >> .ssh/authorized_keys

so that the owner can read and write to the file 

chmod 600 .ssh/authorized_keys

To set the owner to  username and the group owner is centos 

sudo chown username:centos .ssh

To set the owner to and the group owner is centos

sudo chown username:centos .ssh/authorized_keys

To copy user 

sudo cp username /home/centos

OR 

sudo rsync -avr username /home/centos

so that all can read, write and execute 

sudo chmod 777 /home/centos/username

To Download the private key file to local pc (using your local terminal) 

scp -i /home/gautamthakur/Download/gautam-demo.pem centos@aws-public-ip:/home/centos/username username

After download the private key to the local PC. So that user can read. (If you have set the password at the time of created the key then provide the password)

chmod 400 username

To access you AWS Server from the local PC

sudo ssh -i private_key_just_created username@you_aws_public_ip

This key that you have created, you can now give that ti the person that you want to access your instance

If you added a password on your key like in demo, you would also need to give your user that password as well.