How do I setup passwordless ssh on AWS

How do I setup passwordless ssh between nodes on AWS cluster

Following steps to setup password less authentication are tested thoroughly for Centos and Ubuntu.

Assumptions:

1. You already have access to your EC2 machine. May be using the pem key or you have credentials for a unix user which has root permissions.
2. You have already setup RSA keys on you local machine. Private key and public key are available at "~/.ssh/id_rsa" and "~/.ssh/id_rsa.pub" respectively.

Steps:

1. Login to you EC2 machine as a root user.

2. Create a new user

   useradd -m <yourname> 
   sudo su <yourname>
   cd 
   mkdir -p ~/.ssh
   touch ~/.ssh/authorized_keys
   

   Append contents of file ~/.ssh/id_rsa.pub on you local machine to ~/.ssh/authorized_keys on EC2 machine.

   chmod -R 700 ~/.ssh
   chmod 600 ~/.ssh/*
   

3. Make sure sshing is permitted by the machine. In file /etc/ssh/sshd_config, make sure that line containing "PasswordAuthentication yes" is uncommented. Restart sshd service if you make any change in this file:

   service sshd restart # On Centos
   service ssh restart # On Ubuntu
   

4. Your passwordless login should work now. Try following on your local machine:

   ssh -A <yourname>@ec2-xx-xx-xxx-xxx.ap-southeast-1.compute.amazonaws.com
   

5. Making yourself a super user. Open /etc/sudoers. Make sure following two lines are uncommented:

   ## Allows people in group wheel to run all commands
   %wheel ALL=(ALL)       ALL
   
   ## Same thing without a password
   %wheel ALL=(ALL)       NOPASSWD: ALL
   

   Add yourself to wheel group.

   usermod -aG wheel <yourname>