[HOW-TO] Use SSH for Server Authentication 🔓

Generating a new SSH Key Pair

1. Run ssh-keygen -t rsa -b 4096
2. When prompted, enter a passphrase
3. SSH keys should be stored in ~/.ssh/

Importing Public Key to Remote Machine

Option #1 - Manual Configuration

1. SSH into remote server, with username + password
2. cd into your /home directory, and mkdir .ssh
3. Copy public key from local to remote machine scp ~/.ssh/my_key.pub user@0.0.0.0:/home/username/.ssh/my_key.pub
4. Append SSH public key to authorized hosts file cat ~/.ssh/my_key.pub >> ~/.ssh/authorized_keys
5. Set permissions for
   • the .ssh directory (read, write, execute): chmod 700 ~/.ssh/
   • and the SSH keys (read, write): chmod 600 ~/.ssh/*

Option #2 - SSH Copy ID Command

Alternatively, the SSH Copy ID command will upload your public key to the remote server and update .ssh/authorized_keys
After generating an SSH key pair, simply run ssh-copy-id user@0.0.0.0 (with your username, IP and any other SSH flags)

Disable Password Authentication

1. Make a backup of the sshdconfig file, before modifying it `sudo cp /etc/ssh/sshdconfig.backup`
2. Turn off password authentication
   • sudo vim /etc/ssh/sshd_config
   • Find #PasswordAuthentication yes and replace with PasswordAuthentication no
   • Save and exit
3. Restart SSH service sudo service ssh restart

Further Links

• The OpenSSH Project: https://www.openssh.com
• SSH-KeyGen Documentation: https://linux.die.net/man/1/ssh-keygen
• Detailed tutorial for SSH-KeyGen: https://www.ssh.com/ssh/keygen
• Short Video Guide, by Corey Schafer: https://youtu.be/vpk_1gldOAE