intro.v1
in intellij -- i am using this --- git@github.com:michael-maldo/docker-notes.git
That string is an SSH Git URL.
git@github.com:michael-maldo/docker-notes.git
It means:
git@github.com → connect to GitHub using SSH, as user git
michael-maldo/docker-notes → owner + repository name
.git → the Git repository endpoint
So in IntelliJ (or any Git client), this implies:
You are authenticating via SSH keys, not username/password.
Your machine must have:
an SSH key (~/.ssh/id_rsa or id_ed25519)
the public key added to GitHub → Settings → SSH keys
Practical implications (important)
- No browser login needed
Once SSH is set up:
git pull
git push
IntelliJ sync
→ all work without prompts.
- This is different from HTTPS
The HTTPS version would be:
https://github.com/michael-maldo/docker-notes.git
That one requires:
either GitHub token
or browser auth popups
SSH is better for DevOps workflows, CI/CD, servers, VPS, etc.
How IntelliJ uses it
When you clone with that URL in IntelliJ:
It runs essentially:
git clone git@github.com:michael-maldo/docker-notes.git
IntelliJ just delegates to your system ssh.
If something breaks, it’s not an IntelliJ problem, it’s almost always:
ssh -T git@github.com
If that fails → SSH setup issue.
Very DevOps-relevant concept
This is the exact same mechanism you’ll use for:
GitHub Actions runners
CI servers
Kubernetes build agents
VPS automation
No passwords, just keys.
Mental model (simple)
Think of it as:
“Log into GitHub as my machine instead of my browser.”
Your laptop/VM is the identity, not you.
That’s why SSH Git URLs are the professional default.
how to setup sshkey access with github?
This is one of those core DevOps skills — once you do this once, you’ll use it everywhere (laptops, VPS, CI runners, cloud VMs).
I’ll give you the clean, modern way (ED25519).
- Check if you already have a key ls -la ~/.ssh
If you see something like:
id_ed25519 and id_ed25519.pub → you already have one
id_rsa and id_rsa.pub → older but still works
If not, generate one.
- Generate a new SSH key ssh-keygen -t ed25519 -C "michael@github"
Press Enter for:
file location (default is fine)
passphrase (recommended, but optional)
This creates:
~/.ssh/id_ed25519 (private key) ~/.ssh/id_ed25519.pub (public key)
- Start ssh-agent and load key eval "$(ssh-agent -s)" ssh-add ~/.ssh/id_ed25519
Now your key is in memory.
- Add public key to GitHub
Copy it:
cat ~/.ssh/id_ed25519.pub
Then:
GitHub → Profile pic → Settings → SSH and GPG keys → New SSH key
Title: Laptop / VPS / Work PC
Key type: Authentication
Paste the key
- Test it ssh -T git@github.com
You should see:
Hi michael-maldo! You've successfully authenticated...
No password. Pure key-based auth.
- Use SSH URLs in IntelliJ
Clone with:
git@github.com:michael-maldo/docker-notes.git
or convert existing repo:
git remote set-url origin git@github.com:michael-maldo/docker-notes.git
Common real-world issues 🔹 “Permission denied (publickey)”
Usually means:
key not added to GitHub
ssh-agent not running
wrong key loaded
Check:
ssh-add -l
🔹 Multiple machines (laptop + VPS + cloud)
Each machine should have its own key.
On VPS:
ssh-keygen -t ed25519 -C "vps-prod"
Add that key to GitHub as well.
This is exactly how:
CI/CD runners
Kubernetes nodes
build servers
authenticate.
Pro tip (very DevOps)
Create ~/.ssh/config:
Host github.com User git IdentityFile ~/.ssh/id_ed25519
Now SSH is deterministic even with multiple keys.
Why this matters for your career
For someone targeting Cloud / Platform / DevOps roles like you:
SSH keys are used for:
GitHub
GitLab
Bitbucket
Ansible
Terraform
CI agents
Kubernetes nodes
Cloud bastion hosts
It’s basically the Unix equivalent of your passport.
Once you understand SSH keys, half of “mysterious infra auth problems” disappear.
what if i lose the private key on my local machine
Great question — and this is exactly the right level of paranoia for DevOps 😄
Short answer:
If you lose your private key, nothing breaks permanently — you just generate a new one.
There is no way to recover a lost private key. By design.
What actually happens if you lose it?
Say your laptop dies and you lose:
~/.ssh/id_ed25519
But GitHub still has your public key.
Result:
You can no longer authenticate from that machine.
GitHub is still secure.
Nobody can “recreate” your private key.
This is good security.
The recovery process (normal workflow)
From a new machine:
-
Generate new key ssh-keygen -t ed25519 -C "new-laptop"
-
Add new public key to GitHub
GitHub → Settings → SSH keys → New key
- Remove old key (optional but recommended)
Delete the lost one from GitHub.
Done. You're back in business.
Important: GitHub is NOT tied to a single key
You can have:
5 machines
10 keys
1 GitHub account
Each key is independent.
This is how companies manage:
dev laptops
CI runners
prod servers
Worst case scenario
The only real danger is:
If someone steals your private key and your machine is compromised.
Then they can push code as you.
Which is why:
passphrases matter
removing old keys matters
one key per machine matters
Professional-grade practices (what seniors do)
- One key per device
Never reuse the same key across machines.
Good:
Laptop → id_ed25519_laptop VPS → id_ed25519_vps CI → id_ed25519_ci
- Descriptive names on GitHub
Instead of:
id_ed25519
Use:
MacBook-Pro-2024 AWS-Build-Runner Home-PC
So when something dies → you know what to delete.
- Passphrase + ssh-agent
Your private key on disk is encrypted. Agent decrypts it in memory only.
This protects you even if disk is stolen.
- For servers: no backups of private keys
Never:
email them
put them in Dropbox
commit them (obviously)
If a server is destroyed:
generate a new key
add it to GitHub
move on
This is the intended lifecycle.
Mental model (important)
Think of SSH keys like physical locks:
Public key = lock on the door (GitHub)
Private key = your key
Lose the key? → Replace the lock. → Make a new key.
You don't panic. You rotate credentials.
That’s literally how real infrastructure works.
Why this is actually good news
Because in real cloud work:
Instances are ephemeral
CI runners are disposable
Laptops get replaced
Containers die constantly
SSH keys are designed for loss, rotation, and renewal.
If losing a key were catastrophic, modern cloud would be impossible.
One-liner summary
Losing your private key is not a disaster. It’s just a credential rotation event. Generate a new one, add it, delete the old one, continue life.
can the public key be used by other machines?
Yes — but not in the way people often think.
Short answer:
The public key can be copied to any number of machines, but it is useless without the matching private key.
What the public key actually does
The public key is just:
“I will accept logins from whoever proves they own the matching private key.”
It’s a lock, not a key.
Anyone can:
see it
copy it
store it
publish it
And it gives them zero power.
Can other machines use my public key?
They can store it, yes. They cannot authenticate with it.
Because authentication requires:
public key (on GitHub) + private key (on your machine)
Without the private key: → mathematically impossible to log in.
Typical real-world layouts GitHub side (server)
Stores:
id_ed25519.pub
Your laptop
Stores:
id_ed25519 (secret)
When you run:
git push
GitHub sends a challenge: Your machine signs it with the private key. GitHub verifies with the public key.
At no point is the private key transmitted.
Important implication (security)
This is why it’s safe to:
paste public keys on websites
commit them in repos
send them in Slack
And why it’s catastrophic to leak:
~/.ssh/id_ed25519
DevOps best practice (this matters)
Even though you could:
copy the same private key to 5 machines
You should never do this.
Because:
you lose traceability
you can't revoke one device
one compromise breaks all
Instead:
Machine Key Laptop id_ed25519_laptop VPS id_ed25519_vps CI runner id_ed25519_ci
All have different private keys. All public keys live on GitHub.
Subtle but powerful concept
Public keys are often treated as:
identities of machines
Not people.
In real infra:
GitHub doesn't know "Michael"
It knows "this cryptographic entity is allowed"
That's why SSH scales to:
millions of servers
zero shared secrets
no passwords
Final mental model
Public key = padlock Private key = the only physical key
You can give everyone the padlock. Only one person can open it.
so if you will multiple private keys -- thenm that corresponds to multiple public keys -- as key pairs
Exactly. 💯 You’ve got it.
Each private key always has exactly one matching public key. That pair is a cryptographic identity.
So:
1 private key → 1 public key → 1 identity
5 private keys → 5 public keys → 5 identities
These are called key pairs.
How this looks in practice
On disk:
~/.ssh/id_ed25519_laptop (private) ~/.ssh/id_ed25519_laptop.pub (public)
~/.ssh/id_ed25519_vps ~/.ssh/id_ed25519_vps.pub
On GitHub:
MacBook-Pro-2024 AWS-VPS CI-Runner
Each line is one public key.
This is why SSH is so powerful
You are not logging in as:
michael / password
You are logging in as:
cryptographic entity #A7F3C9...
Which happens to be on your laptop.
Important invariant (never breaks)
You can derive the public key from the private key. You can NEVER derive the private key from the public key.
One-way math.
That’s the entire security model.
Advanced but very real DevOps detail
You can even regenerate a public key from a private one:
ssh-keygen -y -f id_ed25519_laptop > id_ed25519_laptop.pub
Meaning:
private key is the source of truth
public key is just a projection
Why seniors insist on one key per machine
Because a key pair = identity.
So if:
a laptop is stolen → revoke only that key
a CI runner is compromised → revoke only that key
a VPS is destroyed → delete only that key
Zero blast radius.
This maps perfectly to cloud concepts
SSH key pairs are basically:
AWS IAM users (but simpler)
GCP service accounts (but local)
Kubernetes cert identities
mTLS certificates
Same pattern:
one identity = one key pair
One-liner that’s worth memorising
Multiple private keys ⇒ multiple public keys ⇒ multiple identities. One key pair = one cryptographic “user”.
at the end of the day --- it is having idividual acoounts -- on ssh keys
Yes — that’s a very good way to think about it. And in fact, that’s exactly how modern systems treat it.
SSH keys are basically individual accounts, just without usernames and passwords.
The real model (what’s actually happening)
In old systems:
username + password = identity
In modern systems:
private key = identity public key = account record
There is no “user” in the human sense. There is only:
“This cryptographic entity is allowed.”
Why this is even better than accounts
Traditional accounts:
need password resets
can be phished
reused everywhere
stored on servers (hashed, but still)
SSH identities:
never transmit secrets
cannot be brute-forced
cannot be guessed
live only on the client
The server (GitHub, Linux, CI) only stores:
a list of trusted public keys
That’s it.
This is literally how cloud works
When you:
ssh ubuntu@ec2-instance
GitHub Actions deploy
Kubernetes node joins cluster
Terraform talks to cloud API
They are not users.
They are:
machine identities with key pairs
Why this mindset is important for you (DevOps)
Because once you see SSH keys as “accounts”, everything clicks:
Concept Old world Modern world Login password private key Account user key pair Revoke access disable user delete public key Audit who logged in which key was used Zero trust impossible native Even more precise mental model
SSH key = service account
Not human. Not personal. Not emotional.
Just:
a cryptographic actor with permissions.
This is why infra feels different from app dev
In app dev you think:
users, sessions, cookies
In infra you think:
identities, trust, keys, certificates
No humans involved.
One sentence that sums it up
SSH keys are individual accounts, but the “person” is a machine, not you.+--++++