How SSH Really Works: A Deep Dive

SSH is something most developers use every day without thinking about it

You run a command and you are inside a server within seconds

But behind that single command there is a clear sequence that makes sure the connection is safe and trusted

The Problem SSH Solves

At a basic level SSH answers one question

How can you connect to a remote machine safely over the internet

The network between you and the server is not secure Anyone can try to read or interfere with data

SSH solves this by combining:

• Secure communication
• Identity verification
• Data protection

All in one flow

What Happens When You Run SSH

When you run

ssh user@server

a few steps happen in order Each step builds trust between your machine and the server

Step 1: Opening the Connection

Your machine connects to the server over the network usually on port 22

At this stage:

• Nothing is encrypted
• No identity is checked

It is just a connection being set up

Step 2: Making the Connection Secure

Now both sides prepare to talk securely

They agree on how to protect the communication and create a shared secret

This secret is never sent over the network

That is why even if someone is watching they cannot understand the data

Step 3: Checking the Server

Before continuing your machine verifies the server

It checks if the server is the same one it connected to before

If this step is skipped someone else could pretend to be the server

Step 4: Verifying You

Now the server checks who you are

In most cases this happens using SSH keys

• Your machine has a private key
• The server has your public key

Your machine proves identity by signing a request and the server verifies it

The private key stays on your machine

Step 5: Starting the Session

Once both sides trust each other the connection becomes fully secure

• Commands are protected
• Outputs are protected
• File transfers are protected

From here it feels like a normal terminal session

Where Problems Usually Start

SSH works well when used by a single person

Issues start when more people are involved

• Keys get shared
• Old access is not removed
• No one knows who has access

The system still works but control is lost

Where SSH Works Well

SSH is fast reliable and widely supported

It is useful for:

• Direct server access
• Debugging
• Running commands remotely

That is why it is still used everywhere

Where It Needs Attention

SSH does not manage access for you

As systems grow you need to think about:

• Who can access
• How access is given
• How access is removed

Without this things become difficult to manage

Practices That Help

• Use key based login instead of passwords
• Do not share private keys
• Remove unused keys regularly
• Limit access at the network level

These habits prevent most issues

Conclusion

SSH is not complicated It follows a clear flow

Connection then secure setup then identity checks and finally a protected session

Once you understand this flow you start using SSH more carefully and avoid common mistakes