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Passwordless SSH Access

Passwordless SSH makes it easy to automate tasks and run tools like Ansible without being prompted for passwords. This guide walks you through generating SSH keys, distributing them, and setting up your environment for seamless, secure access.

Requirements​

  • A local Linux/macOS system (your control device)
  • Remote machines accessible via SSH
  • OpenSSH installed on all machines

Before beginning, you will first need to be able to SSH to your target machines WITH a password. This might be done with a user on that machine you have a password for and network access with a hostname.

For example:

ssh user@hostname

This assumes, that the target machine is on the local network and has the OpenSSH daemon running.

🗝️ Generate an SSH key (if you haven't already)​

ssh-keygen -t ed25519 -f ~/.ssh/homelab

Hit Enter when prompted for a passphrase (or add one for security).

Copy your public key to each remote host​

ssh-copy-id -i ~/.ssh/homelab.pub username@10.0.0.2
ssh-copy-id -i ~/.ssh/homelab.pub username@10.0.0.3
ssh-copy-id -i ~/.ssh/homelab.pub username@10.0.0.4

Replace user@IP with the correct user and IP of each node.

Configure your SSH client​

Create or edit ~/.ssh/config:

vim ~/.ssh/config

Paste the following:

AddKeysToAgent yes

Host node-1
  HostName 10.0.0.2
  User username
  IdentityFile ~/.ssh/homelab
  Port 22

Host node-2
  HostName 10.0.0.3
  User username
  IdentityFile ~/.ssh/homelab
  Port 22

Host node-3
  HostName 10.0.0.4
  User username
  IdentityFile ~/.ssh/homelab
  Port 22

Now you can run ssh node-1 instead of ssh username@10.0.0.2.

Auto-load SSH key on login​

Add this to your ~/.zshrc (or ~/.bashrc if using bash) - make sure to replace the key name with your own if it differs:

# Start SSH Agent, add key
if ! pgrep -u "$USER" ssh-agent > /dev/null; then
  eval "$(ssh-agent -s)"
  ssh-add ~/.ssh/homelab 2>/dev/null
fi

Then reload your shell:

source ~/.zshrc

Test it out​

ssh node-1

You should now be able to log in without entering a password or passphrase.