SSH

What is SSH?

SSH, or Secure Shell, is a network communication protocol that enables two computers/devices to communicate and share data.

2. Why is it called a Secure Shell?

Because communication between the host and client will be in an encrypted format.

3. More about SSH

The default port for SSH client connections is 22

We can change the default port and use one between 1024 and 32,767

SSH is also a command in Linux

It is used to access another Linux server or to access a Linux server from a terminal.

Syntax: ssh user_name@host(IP/Domain_name)

4. How to use SSH?

To use SSH, the SSH service must be installed on the Linux server
You can check using
rpm -qa | grep ssh, or
check the file /etc/ssh/sshd_config

If not already installed, then install the two
install openssh-clients openssh-server

and now enable SSH or check if it is enabled using
systemctl status sshd

5. Examples

-Access Linux server using Putty(free open source tool)
-Access a Linux server from another server

6. There are two ways to access a remote server

— without password(by passing the ssh key)

— by using password

a. How to access a remote server without
password?

If you frequently access the server, then it’s a good idea to
configure your SSH keys so that you can log in without
password.

Follow the steps below

1. Generate A New SSH Key Pair on the local machine.
2. Copy the public key to the remote machine.
3. Log in to the remote server without password.

Step1: Generate an SSH key using

ssh-keygen

You can check the generated keys using

ls -l.ssh
cat ~/.ssh/id_rsa.pub

Step2: Copy your public SSH key to remote server,
( on remote server it is copied under
~/.ssh/authorizedkeys file)

ssh-copy-id root@192.168 …

Step3: Now connect without the server password

ssh username@SERVER_IP

SSH will authenticate using your key.

Step4: Even easier step you can do: create an SSH alias

nano ~/.ssh/config

Host myserver
    HostName SERVER_IP
    User username
    IdentityFile ~/.ssh/id_ed25519

Then simply:

ssh myserver

And then Proceed. This way you can acess remote server without password.

b. With password

Step1: Connect to the server

From WSL/Ubuntu:

ssh username@SERVER_IP

For example:

ssh root@192.168.1.100

Step2: Enter the password

You’ll see:

root@192.168.1.100's password:

Type the server password and press Enter.

The password won’t appear on the screen while you type. That’s normal.

Step3: You’re connected

You’ll get something similar to:

root@server:~

Now commands you run are executing on the remote server, not your own Windows PC.

To disconnect

exit

So the basic flow is:

Your PC/WSL
     ↓
ssh username@SERVER_IP
     ↓
Enter server password
     ↓
Remote Linux Server

If you’re doing the SSH Remote Server Setup project, password authentication is useful initially, but the project specifically practices SSH key-based access afterward.

Thanks for reading..Happy coding.