Connect to the master node using SSH

To configure the key pair private key file permissions

Before you can use your Amazon EC2 key pair private key to create an SSH connection, you must set permissions on the .pem file so that only the key owner has permission to access the file. This is required for creating an SSH connection using terminal or the Amazon CLI.

1. Ensure you've allowed inbound SSH traffic. For instructions, see Before you connect: Authorize inbound traffic.

2. Locate your .pem file. These instructions assume that the file is named mykeypair.pem and that it is stored in the current user's home directory.

3. Type the following command to set the permissions. Replace ~/mykeypair.pem with the full path and file name of your key pair private key file. For example C:\Users\<username>\.ssh\mykeypair.pem.

   chmod 400 ~/mykeypair.pem

   If you do not set permissions on the .pem file, you will receive an error indicating that your key file is unprotected and the key will be rejected. To connect, you only need to set permissions on the key pair private key file the first time you use it.

To connect to the master node using the terminal

1. Open a terminal window. On Mac OS X, choose Applications > Utilities > Terminal. On other Linux distributions, terminal is typically found at Applications > Accessories > Terminal.

2. To establish a connection to the master node, type the following command. Replace ec2-###-##-##-###.compute-1.amazonaws.com.cn with the master public DNS name of your cluster and replace ~/mykeypair.pem with the full path and file name of your .pem file. For example C:\Users\<username>\.ssh\mykeypair.pem.

   ssh hadoop@ec2-###-##-##-###.compute-1.amazonaws.com.cn -i ~/mykeypair.pem

   Important

   You must use the login name hadoop when you connect to the Amazon EMR master node; otherwise, you may see an error similar to Server refused our key.

3. A warning states that the authenticity of the host you are connecting to cannot be verified. Type yes to continue.

4. When you are done working on the master node, type the following command to close the SSH connection.

   exit

To connect to the master node using PuTTY

1. Ensure you've allowed inbound SSH traffic. For instructions, see Before you connect: Authorize inbound traffic.

2. Open putty.exe. You can also launch PuTTY from the Windows programs list.

3. If necessary, in the Category list, choose Session.

4. For Host Name (or IP address), type hadoop@MasterPublicDNS. For example: hadoop@ec2-###-##-##-###.compute-1.amazonaws.com.cn.

5. In the Category list, choose Connection > SSH, Auth.

6. For Private key file for authentication, choose Browse and select the .ppk file that you generated.

7. Choose Open and then Yes to dismiss the PuTTY security alert.

   Important

   When logging into the master node, type hadoop if you are prompted for a user name .

8. When you are done working on the master node, you can close the SSH connection by closing PuTTY.

   Note

   To prevent the SSH connection from timing out, you can choose Connection in the Category list and select the option Enable TCP_keepalives. If you have an active SSH session in PuTTY, you can change your settings by opening the context (right-click) for the PuTTY title bar and choosing Change Settings.

To connect to the master node using the Amazon CLI

1. Ensure you've allowed inbound SSH traffic. For instructions, see Before you connect: Authorize inbound traffic.

2. To retrieve the cluster identifier, type:

   aws emr list-clusters

   The output lists your clusters including the cluster IDs. Note the cluster ID for the cluster to which you are connecting.

   "Status": {
       "Timeline": {
           "ReadyDateTime": 1408040782.374,
           "CreationDateTime": 1408040501.213
       },
       "State": "WAITING",
       "StateChangeReason": {
           "Message": "Waiting after step completed"
       }
   },
   "NormalizedInstanceHours": 4,
   "Id": "j-2AL4XXXXXX5T9",
   "Name": "AWS CLI cluster"

3. Type the following command to open an SSH connection to the master node. In the following example, replace j-2AL4XXXXXX5T9 with the cluster ID and replace ~/mykeypair.key with the full path and file name of your .pem file (for Linux, Unix, and Mac OS X) or .ppk file (for Windows). For example C:\Users\<username>\.ssh\mykeypair.pem.

   aws emr ssh --cluster-id j-2AL4XXXXXX5T9 --key-pair-file ~/mykeypair.key						

4. When you are done working on the master node, close the Amazon CLI window.

   For more information, see Amazon EMR commands in the Amazon CLI. If you're experiencing difficulty with using SSH to connect to your master node, see Troubleshoot connecting to your instance.