SSH Configuration

The Hadoop control scripts (but not the daemons) rely on SSH to perform cluster-wide operations. For example, there is a script for stopping and starting all the daemons in the cluster. Note that the control scripts are optional—cluster-wide operations can be performed by other mechanisms, too (such as a distributed shell).

To work seamlessly, SSH needs to be set up to allow password-less login for the hadoop user from machines in the cluster. The simplest way to achieve this is to generate a public/private key pair and place it in an NFS location that is shared across the cluster.

First, generate an RSA key pair by typing the following in the hadoop user account:

% ssh-keygen -t rsa -f ~/.ssh/id_rsa