DevOps Classroom notes 28/Jan/2026

Password Based SSH connectivity between two linux machines

• For this lab exercise i will be using Azure Account to create virtual machines
• We have create two ubuntu linux instances (node-1, node-2)
• From a client execute ssh username@ip-or-name and enter credentials
• On node 1 and node 2 lets create a new user called as myuser

sudo adduser myuser

• on your laptop if you dont have keys in ~/.ssh execute ssh-keygen
• i have generated temp_ed25519
• Now i want to upload the public key for myuser on node1 and node2

ssh-copy-id -i ~/.ssh/temp_ed25519 myuser@<node-1-ip>
ssh-copy-id -i ~/.ssh/temp_ed25519 myuser@<node-2-ip>

• once th copy is success we can login into node 1 and node 2 without password

 ssh -i ~/.ssh/temp_ed25519 myuser@<node-1-ip>
 ssh -i ~/.ssh/temp_ed25519 myuser@<node-2-ip>

How Ansible uses ssh

• Ansible expect python on nodes, Ansible uses SSH + Python
• When you run ansible, it reads the ip addresses and credential info from inventory which indirectly specify SSH options
• Ansible internally runs a SSH command
• Generates a temporary python script (for your configuration) copies that to node
• Python on node executes this script
• output of that is returned via SSH
• Then it cleans up the temporary python script and other files
• As a user of ansible we create playbook or adhoc-command to make ansible work.
• It is recommended to configure a user on all nodes with key based SSH to work in Ansible as industry standard. This user generally has sudo or privilege escallation.