How to use ssh-key for authentication

Create ssh key pair

open git-bash and generate a new key pair.

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

Adding SSH key to ssh-agent

start the ssh-agent in the background

eval $(ssh-agent -s)
  Agent pid 59566

Add your SSH private key to the ssh-agent. If you created your key with a different name, or if you are adding an existing key that has a different name, replace id_rsa in the command with the name of your private key file.

ssh-add ~/.ssh/id_rsa

To view keys added in ssh-agent.

ssh-add -l
output:
  2048 SHA256:+yAau/t+ntQreP7UhewhWeelFqsYqqaL+qyoEjH2VBo ~/.ssh/id_rsa (RSA)

ssh-add -lE md5
output:
  2048 MD5:cf:cf:36:4e:a2:fd:31:b1:11:89:7d:1e:27:be:27:dd ~/.ssh/id_rsa (RSA)

Use ssh key to access git repository

Add public key to github account or a specific repository.

Clone the repository with SSH url in the same shell session that ssh-agent is running.

Use ssh key to login server

Once an SSH key has been created, the ssh-copy-id command can be used to install it as an authorized key on the server. Once the key has been authorized for SSH, it grants access to the server without a password.

Run the following command on your local computer to copy public ssh key to remote server:

ssh-copy-id -i ~/.ssh/id_rsa.pub <user_name>@<remote_host_ip>

This logs and copies keys to the remote server, and configures them to grant access by adding them to the authorized_keys file in ~/.ssh/ directory.

The copying may ask for a password or other authentication for the server.

Note

Only the public key is copied to the server. The private key should never be copied to another machine.

Test the new key

Once the key has been copied, you can login the remote serer with ssh command on your local computer:

ssh -i ~/.ssh/id_rsa <user_name>@<remote_host_ip>