My Geek Notes

This is a very simple howto (for Linux/Mac users) on setting up both SSH client side and server side keys. Using private and public keys for ssh, scp, and sftp is great for a series of reasons.

1. You can give someone your public key to put on their server so you have access. I just did this the other night. As soon as I was done he simply removed my key - no passwords had to be shared.
2. It allows for better security so you don’t have someone trying to guess passwords or dealing with someone who can’t remember the password and does the “sticky note with password on monitor” trick.
3. If you choose to not use a passphrase on your keys, you can use it with automated processes that require using scp.

That being said, here are the simple steps.

On the client:

mkdir -p ~/.ssh
chmod 700 ~/.ssh
ssh-keygen -q -f ~/.ssh/id_rsa -t rsa
# here you'll be asked to create a passphrase, optionally it can be left blank
scp ~/.ssh/id_rsa.pub yourserver.com:

On the server:

mkdir -p ~/.ssh
chmod 700 ~/.ssh
cat ~/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys
rm -f ~/id_rsa.pub

Also you should note some important settings in your server’s sshd_config file:

PubkeyAuthentication yes            # yes to allow priv/pub key auth
PasswordAuthentication no           # no to ONLY allow priv/pub key auth
ChallengeResponseAuthentication no  # no to ONLY allow priv/pub key auth

If you make any changes to your sshd_config file, you’ll need to restart the SSH server.

OpenSSH authentication, keys, scp, sftp, SSH