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on-ssh-passwordless

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To set up passwordless SSH login between two servers, typically with public key authentication, follow these steps:

  1. Generate an RSA key pair on the server you’re copying from:
ssh-keygen -t rsa -b 4096 -C "username@hostname"
  1. Copy the public key to the destination server using ssh-copy-id:
ssh-copy-id user@destination-server

Or, if ssh-copy-id is not available, manually copy the public key from your local .ssh/id_rsa.pub file:

cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
chown -R `whoami`:`whoami` ~/.ssh
  1. Configure sshd_config on the destination server if necessary, such as setting PermitRootLogin and PasswordAuthentication, which you might want to disable for security reasons:
   sudo cat << EOF > /etc/ssh/sshd_config
   # Custom configuration options...
   PasswordAuthentication no
   PermitRootLogin no
   # ...
   EOF
  1. Restart the SSH service on both servers:
sudo systemctl restart sshd

Now, you should be able to log in from one server to another using just your private key:

ssh user@destination-server

You’ll be prompted once to confirm the public key fingerprint on the destination server. After that, SSH login will be passwordless.

Note: The specific commands might vary slightly based on your Linux distribution and version or if you’re running macOS or Windows using Cygwin, Git Bash, etc. Always refer to your system’s documentation for precise steps.

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