step-by-step guide to setting up SSH passwordless login¶

Step 1: Generate SSH Keys on Client¶

On the Client Machine¶

Run the following command to generate SSH keys:

1	`ssh-keygen -t rsa`

This will create a pair of files: id_rsa (private key) and id_rsa.pub (public key).

Step 2: Copy Public Key to Server¶

Using SSH-Copy-ID¶

Run the following command to copy the public key to the server:

1	`ssh-copy-id username@server_ip`

Replace username with your actual username and server_ip with the IP address of your server.

Manual Method¶

If ssh-copy-id is not available, you can copy the public key manually:

1	`scp ~/.ssh/id_rsa.pub username@server_ip:~/`

Then, log in to the server and append the public key to the authorized_keys file:

cat ~/id_rsa.pub >> ~/.ssh/authorized_keys

Alternative way of adding keys¶

Add GitHub user public keys to `authorized_keys`¶

If you want to add all public keys for a GitHub user (convenient for provisioning accounts), GitHub exposes them at https://github.com/<username>.keys. (no login required)

Local (on the server) using curl:

mkdir -p ~/.ssh
chmod 700 ~/.ssh
curl -s https://github.com/GITHUB_USERNAME.keys >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys

Local (on the server) using wget:

mkdir -p ~/.ssh
chmod 700 ~/.ssh
wget -qO- https://github.com/GITHUB_USERNAME.keys >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys

Remote (from your client) using ssh + curl:

ssh username@server_ip 'mkdir -p ~/.ssh && chmod 700 ~/.ssh && curl -s https://github.com/GITHUB_USERNAME.keys >> ~/.ssh/authorized_keys && chmod 600 ~/.ssh/authorized_keys'

Remote (from your client) using ssh + wget:

ssh username@server_ip 'mkdir -p ~/.ssh && chmod 700 ~/.ssh && wget -qO- https://github.com/GITHUB_USERNAME.keys >> ~/.ssh/authorized_keys && chmod 600 ~/.ssh/authorized_keys'

Replace GITHUB_USERNAME with the GitHub account name whose public keys you want to add. These commands create the .ssh folder if missing and set safe permissions.

Step 3: Configure SSH Server¶

Edit SSHD Config¶

Edit the SSH server configuration file (usually /etc/ssh/sshd_config) and ensure the following lines are uncommented:

1 2	`PubkeyAuthentication yes AuthorizedKeysFile .ssh/authorized_keys`

Restart the SSH server to apply changes:

sudo service ssh restart

Connect to Server¶

Try connecting to the server using SSH:

1	`ssh username@server_ip`

You should be logged in without being prompted for a password.