Remote Control Linux Client using Passwordless SSH

Suppose the hostname of five client nodes are compute-1, compute-2, compute-3, compute-4, and compute-5.

Step 1. Create the authentocation key on Remote SSH for accessing to client or computing node.

Use ssh-keygen to generate authentication key.

ssh-keygen

Then you are asked to set where you want to save the key files. Just Enter to use default setting.

Generating public/private rsa key pair.

Enter file in which to save the key (/home/rangsiman/.ssh/id_rsa):

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Enter three times to use default value. Then you will get the warning message. Now it's finished.

The key fingerprint is:

--------------------------------------------------- rangsiman@RemoteSSH

The key's randomart image is:

+--[ RSA 2048]----+

| .==. E          |

| o.o.* =         |

|. o = =          |

| + o . +         |

|  + +   S        |

|   o o .         |

|    .            |

|                 |

|                 |

+-----------------+

Look at $HOME/.ssh/. There you should have id_ras and id_ras.pub files. Now, copy id_ras.pub to authorized_keys file.

cp id_ras.pub authorized_keys

Step 2. Create automatic script to send token authentication key to all clients.

On Remote SSH, create new bash script and copy/paste following code to bash script.

cd $HOME/.ssh

for i in compute-{1..5}

do

scp -r id_ras id_rsa.pub authorized_keys $USER@$i:$HOME/.ssh/

done

Step 3. Run script

Change permission of script using

chmod +x bash_script.sh

You also must change the hostname of client before run the script !

Then run script

./bash_script.sh

Files specified in scp line will be sent to compute-1, compute-2, compute-3, compute-4, and compute-5.

When it's done, you are able to access to client using SSH passwordless.

Rangsiman Ketkaew

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