Permission Denied error while running start-dfs.sh

Question

I am getting this error while performing start-dfs.sh

Starting namenodes on [localhost] 
pdsh@Gaurav: localhost: rcmd: socket: Permission denied 
Starting datanodes
pdsh@Gaurav: localhost: rcmd: socket: Permission denied
Starting secondary namenodes [Gaurav]
pdsh@Gaurav: Gaurav: rcmd: socket: Permission denied 2017-03-13 09:39:29,559 
WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable

Using hadoop 3.0 alpha 2 version.

Any help is appreciated

Answer 1

I also encountered the same thing, I did so I found that my pdsh default rcmd is rsh, not ssh, rsh and ssh remote login authentication is not the same, when installing hadoop I configured ssh localhost password-free login, but rsh is not possible.

so，try：

1.check your pdsh default rcmd rsh

pdsh -q -w localhost

See what your pdsh default rcmd is.

2.Modify pdsh's default rcmd to ssh

export PDSH_RCMD_TYPE=ssh

you can be added to ~/.bashrc, and source ~/.bashrc

3.sbin / start-dfs.sh

Answer 2

Uninstall pdsh will solve this problem. I am working with Hadoop version 3.2.1 on Ubuntu 18.04.4 LTS.

I test start-dfs.sh on several fresh-installed virtual machines and one old VM. The command failed only on the old VM. I have tried the high-voted answer, and found that only the old VM has pdsh installed. So I uninstall this software, and after that the command executed successfully.

So, if you did not install pdsh for some purpose, you can try to uninstall it.

Answer 3

Try uninstalling pdsh

sudo apt-get remove pdsh

and then restart your hadoop by:

sudo start-dfs.sh

This is what worked for me.

Answer 4

A sudo user could also change pdsh's Rcmd type to ssh via the command:

echo "ssh" | sudo tee /etc/pdsh/rcmd_default