Normal SSH gateway requires the password to be entered each time when a service tries to connect to any node. This will slow down the process to a great extent. Usually, Passwordless ssh is getting set up in distributed technology, where always node to node communication must be faster. As we know that Hadoop is fully distributed the technology. All data getting a store in multiple commodity hardware, so there must be faster communication with each other. Actually, Hadoop is working on the Master-Slave architecture. When a client needs to store or access the data from HDFS, then its submit request to Master node then the master node distributing the request to multiple Slave nodes. Mean if we are not doing Passwordless ssh setup then for every client request Master will need to login slaves via credentials. Is this really feasible for faster data processing? Of course No.
That’s why we need the Passwordless ssh setup in Hadoop to make it feasible. Master will not need to log in the slaves, it will directly go to the slave address and will fetch or store the required data.