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Beginner Topic 16 of 50 DevOps & Tooling

SSH Keys

Key-based remote login.

How it works

SSH uses public-key cryptography to authenticate without sending a password. ssh-keygen creates a key pair, commonly Ed25519: the private key stays on your machine, ideally protected by a passphrase, and the public key is added to the authorized_keys file in the .ssh folder of the server account. During login the server challenges the client, which proves possession of the private key by signing. The known_hosts file records server fingerprints so a changed host is flagged. ssh-agent holds unlocked keys, and the config file defines hosts, users and jump hosts. The same keys authenticate to Git hosting services.

Where it is used

They secure remote administration, deployments, tunnels and automated jobs, and are far safer than passwords because they cannot be guessed or phished in the same way.

Common pitfall

Sharing or committing a private key, leaving it without a passphrase on a laptop and keeping old keys in authorized_keys all create risk. File permissions must be strict, typically 600 for the private key. Rotate keys, one per device, and disable password login on servers.

Where it fits in the course

SSH Keys is topic 16 of 50 in DevOps & Tooling, rated Beginner. It follows Cron Jobs. The next topic is Build Systems.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the DevOps & Tooling quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is SSH Keys?
Key-based remote login. It belongs to DevOps & Tooling and is a beginner-level topic.
Where do people use SSH Keys?
They secure remote administration, deployments, tunnels and automated jobs, and are far safer than passwords because they cannot be guessed or phished in the same way.
What is the most common mistake with SSH Keys?
Sharing or committing a private key, leaving it without a passphrase on a laptop and keeping old keys in authorized_keys all create risk.
What should I learn before this topic?
Start with Cron Jobs, the topic just before it in DevOps & Tooling.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the DevOps & Tooling quiz.
Is SSH Keys hard to learn?
It is a Beginner topic, so it works as an entry point. If the terms are new, read the explanation twice and try the visualizer before the quiz.
How long does it take to learn SSH Keys?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to SSH Keys?
Cron Jobs, Build Systems, grep, sed and awk are closely connected. The full list is in the related topics section of this page.
What should I study after SSH Keys?
Continue with Build Systems, the next topic in DevOps & Tooling.

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