Add ssh key file for linux server - Key generated, then what?

Question

I want to build a CentOS7 server by myself.

Now I already followed the steps mentioned in this link: https://www.digitalocean.com/community/tutorials/initial-server-setup-with-centos-7, which includes

1. generated my new key .pub file using keygen.
2. add its content start with "ssh-rsa" to .ssh/authorized_keys
3. chmod the key and the .ssh folder,
4. configure sshd using vi /etc/ssh/sshd_config
5. use systemctl reload sshd to restart sshd.

At this point, I thought the future ssh operations from my client host should already need the key to do the log in. However, at this point I can still using ssh to log in my server with only password.

Are there any special procedure that I miss?

Answer 1

Open sshd configuration file and uncomment or add line PasswordAuthentication no. Restart sshd service.

Answer 2

2. add its content start with "ssh-rsa" to .ssh/authorized_keys

No... This should go on the remote system. On your personal system you keep the private key, and you add the public key to all the /home/<user>/.ssh/authorized_keys of all systems/userids you want to access using the key. This can be done 'manually' or using ssh-copy-id, typically:

ssh-copy-id -i ~/.ssh/your_key.pub remote-host

or

ssh-copy-id -i ~/.ssh/your_key.pub user@remote-host

if this is a different userid.

If you do it manually, make sure that you keep the correct authorization flags on all files and .ssh directories (should be R/W strictly for that user only, no access whatsoever by anyone else).