1. When creating an EC2 instance, you have a chance to download key pair (.pem file) for the instance
2. The pem file is the private key for accessing the EC2 instance. Change the extension .pem to .ppk
3. Install and open putty.
Host Name: the public DNS of the EC2 instance. e.g ubuntu@ec2-54-148-40-159.us-west-2.compute.amazonaws.com
The 'ubuntu' here is the default user name. Different linux distribution has different default username
Connections->SSH->Auth:
Choose the .ppk file as the private key
4. Click Ok to connect to the server
5. Add a new user group ('hadoop') and user ('hduser') for running hadoop
sudo addgroup hadoop
sudo adduser --ingroup hadoop hduser
6. Add sudo previlege to hduser
sudo adduser hduser sudo
7. Switch to user hduser
su hduser
here we switch to hduser so the following step will generate keys for this user
8. On the EC2 instance, the SSH software has been installed, so just use it to generate private - public keys
ssh-keygen -t rsa
The command will generate id_rsa (private key) and id_rsa.pub (public key) under /home/hduser/.ssh directory
Leave the password empty if you don't need protection to the keys
9. To be able to SSH to another EC2 instance, you need to copy the public key (i.e. id_rsa.pub) to the target instance.
9.1 set up hduser on the target EC2 instance
9.2 enable password access to the target EC2 instance (this is not safe to will disable later)
putty to the target instance
sudo vi /etc/ssh/sshd_config
change "PasswordAuthentication no" to "PasswordAuthentication yes"
reboot the instance, sudo reboot
9.3 go back to the original EC2 instance
ssh-copy-id -i /home/hduser/.ssh/id_rsa.pub hduser@target_instance_address
it will ask for the password.
this command will copy the public key to the target instance under /home/hduser/.ssh/authorized_keys
9.4 from the original EC2 instance, test connection to target instance
ssh hduser@target_instace_address
it should just connect without asking for password
9.5 disable password access on the target instance
simply change 'yes' to 'no'
10. repeat the process 9 for all the slave instances, so from the master instance it can ssh to any slave without password
also there are other ways (e.g. pscp) to copy public key to target instance, ssh-copy-id is not the only way