🔐 Setting Up SSH Keys on Linux (Step-by-Step Guide)

Using SSH keys is a safer and easier way to connect to Linux servers — no more typing your password every time. This guide will help you set up SSH keys, copy them to a remote server, and log in securely.

✅ Step 1: Check If You Already Have SSH Keys

Open your terminal and run:

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ls ~/.ssh/id_*.pub

If you see a file like id_ed25519.pub or id_rsa.pub, it means you already have a key. You can use that one or create a new one.

🛠 Step 2: Create a New SSH Key Pair

To make a new SSH key, run:

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ssh-keygen -t ed25519 -C "your_email@example.com"

On older systems, use ssh-keygen -t rsa -b 4096 instead.

• Press Enter to accept the default location (~/.ssh/id_ed25519)
• You can choose to add a passphrase (or leave it empty)

This creates two files:

• id_ed25519 → your private key (keep it secret!)
• id_ed25519.pub → your public key (you’ll share this)

📤 Step 3: Add Your Public Key to the Remote Server

Option 1: Use ssh-copy-id (recommended)

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ssh-copy-id username@remote_server_ip

Add Your Public Key to the Remote ESXI Server

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cat ~/.ssh/id_rsa.pub | ssh root@ESXI_IP 'cat >> /etc/ssh/keys-root/authorized_keys'

This command adds your key to the remote server so you can log in without a password.

Option 2: Manual method

1. Show your public key:

   1	cat ~/.ssh/id_ed25519.pub

2. Copy the whole line

3. Connect to your server and paste it into:

   1	nano ~/.ssh/authorized_keys

🚀 Step 4: Log In Without a Password

Now try logging in:

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ssh username@remote_server_ip

If everything is correct, you’ll connect without entering a password 🎉

🔒 Step 5 (Optional): Turn Off Password Login

This step is for extra security. Only do it if SSH keys are working!

1. Open SSH settings on the server:

   1	sudo nano /etc/ssh/sshd_config

2. Find and change these lines:

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   PasswordAuthentication no ChallengeResponseAuthentication no UsePAM no

3. Save and restart SSH:

   1	sudo systemctl restart sshd

💡 Helpful Tips

• Your private key must stay private (~/.ssh/id_ed25519)
• A passphrase adds extra protection
• Use an SSH config file to manage many servers:

Create or edit this file:

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nano ~/.ssh/config

Add this block:

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Host myserver
  HostName 192.168.1.10
  User vitalii
  IdentityFile ~/.ssh/id_ed25519

Then you can connect by simply running:

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ssh myserver

🧩 Summary

SSH keys help you:

• Log in faster
• Avoid typing passwords
• Stay secure

Now you’re ready to manage your servers like a pro — safely and efficiently!