Ubuntu configuring SSH Key-based Authentication

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SSH key-based authentication is a more secure way to log in to a remote server than using a password. It uses a pair of private and public keys to authenticate the user, rather than a password. In this way, only the user who has the private key can log in to the server.

Here are the steps to configure SSH key-based authentication on Ubuntu:

  1. On your local machine, generate a new SSH key pair by running the following command:
ssh-keygen -t rsa

This will generate a new private key and a public key. The private key should be kept secure and should not be shared with anyone.

  1. Copy the public key to the remote server. You can use the ssh-copy-id command to do this. For example, to copy the key to a remote server with IP address 192.168.0.100, you would run the following command:
ssh-copy-id user@192.168.0.100

This will copy your public key to the remote server and append it to the ~/.ssh/authorized_keys file.

  1. On the server, edit the /etc/ssh/sshd_config file and set PasswordAuthentication to no and PubkeyAuthentication to yes.
sudo nano /etc/ssh/sshd_config

Then

PasswordAuthentication no
PubkeyAuthentication yes
  1. Restart the SSH daemon on the server to apply the changes.
sudo systemctl restart ssh
  1. Test the connection by running the following command on your local machine
ssh user@192.168.0.100

You should be logged in to the remote server without being prompted for a password.

It’s important to note that you can also use SSH-keys on other Linux distributions like Centos, OpenSUSE and Debian. You will have to check the specific steps for each distribution on their official documentation.

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