How to set up key login for ubuntu ssh

To set up SSH key-based login on an Ubuntu system, you'll need to generate an SSH key pair, add the public key to the remote server, and configure the SSH server to allow key-based authentication. Here's a step-by-step guide:

1. Generate an SSH Key Pair (if you don't already have one):

Open a terminal on your local machine and run the following command to generate an SSH key pair (if you haven't done this already):

ssh-keygen -t rsa -b 4096

Follow the prompts to specify the key's location and set a passphrase if you'd like.

2.Copy the Public Key to the Remote Server:

Use the ssh-copy-id command to copy your public key to the remote server. Replace username and remote_server with the appropriate values:

ssh-copy-id username@remote_server

You'll need to enter the password for the remote user when prompted. This command will copy your public key to the remote server's ~/.ssh/authorized_keys file.

3.Configure SSH Server for Key-Based Authentication:

On the remote server, you need to make sure SSH is configured to allow key-based authentication. Edit the SSH server configuration file:

sudo nano /etc/ssh/sshd_config

Find the following lines and make sure they are set as shown:

PubkeyAuthentication yes
PasswordAuthentication no
ChallengeResponseAuthentication no
UsePAM no

Save the file and then restart the SSH server:

sudo service ssh restart

4.Test the Key-Based Login:

Now you should be able to log in using your SSH key:

ssh username@remote_server

If you've set a passphrase for your SSH key, you'll be prompted to enter it.

Remember to keep your private key secure, and don't share it with anyone. Using SSH key-based authentication is more secure than password-based authentication, as it eliminates the need for passwords and relies on cryptographic keys.