SSH Key Authentication Setup Guide

🎯 Goal:

Enable secure, passwordless SSH login from your client machine to your server using SSH key authentication.

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🧱 Prerequisites:

• You have access to both your client machine (where you initiate the SSH connection) and your server.

• You know the server's IP address or hostname.

• You have user credentials on the server (e.g., root or another user).

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1️⃣ Generate an SSH Key on Your Client

On your client machine (the one you'll connect from), open a terminal and run:

• Press Enter to accept the default save path: ~/.ssh/<name>.

• You can set a passphrase or leave it empty for passwordless use.

This generates:

• ~/.ssh/<name>→ your private key (keep safe!)

• ~/.ssh/<name>.pub → your public key (to share with the server)

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2️⃣ Copy Your Public Key to the Server

✅ Preferred (Automatic) Method:

On your client, run:

Replace:

• ~/.ssh/my_custom_key.pub → with the full path to your public key (.pub file)

• username → your server's username

• server_ip → your server's IP address or hostname

You’ll be prompted for your server password once.

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✋ Manual Method (If ssh-copy-id isn’t available):

Step A: View and copy your public key

Copy the entire output.

Step B: Log into your server

Step C: Paste the key into authorized_keys

On the server, run:

Paste the key you copied earlier, then save and exit.

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3️⃣ Set Permissions on the Server

Still on the server, run:

This ensures the key will be accepted by the SSH service.

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4️⃣ Test Your SSH Login

On your client machine, try:

✅ If everything is set up correctly, you should be logged in without being asked for a password.

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🔐 Optional: Disable Password Authentication on the Server

To improve security, you can disable password logins entirely:

1. Edit the SSH config on your server:

2. Find and change (or add) the following lines:

3. Restart SSH:

⚠️ Make sure your SSH key login works before doing this or you could lock yourself out.