How Does SSH Work in Linux Step by Step?

Secure Shell (SSH) is a widely used cryptographic network protocol for secure data communication over unsecured networks. It provides a secure channel between two networked devices by encrypting data that is sent between them. SSH is commonly used in Linux systems for remote access and file transfer. In this article, we will take a step-by-step look at how SSH works in Linux.

Table of Contents

1. What is SSH?
2. How Does SSH Work?
3. How to Use SSH in Linux
4. More Examples

What is SSH?

SSH is a protocol that enables secure communication between two devices over an unsecured network. It is used to establish a secure connection for remote access and file transfer. The protocol is designed to prevent eavesdropping, tampering, and message forgery.

How Does SSH Work?

SSH works by using a public key and a private key pair. The public key is stored on the server, while the private key is stored on the client. When a client wants to connect to the server, it sends its public key to the server. The server then encrypts a random message using the client's public key and sends it back to the client. The client decrypts the message using its private key and sends it back to the server. This process is called the key exchange.

Once the key exchange is complete, the client and server can communicate securely. SSH uses a symmetric encryption algorithm to encrypt data sent between the two devices. The encryption algorithm is negotiated during the key exchange.

How to Use SSH in Linux

Using SSH in Linux is relatively easy. First, make sure that the OpenSSH server is installed on the server. You can check if it is installed by running the following command:

sudo apt-get install openssh-server

Once the OpenSSH server is installed, you can connect to it using the SSH client. The SSH client is usually pre-installed on most Linux distributions. To connect to the server, use the following command:

ssh username@server_address

Replace username with your username on the server and server_address with the IP address or hostname of the server. You will be prompted for your password. Once you enter your password, you will be logged into the server.

More Examples

You can also use SSH to transfer files between two devices. To transfer a file from the client to the server, use the following command:

scp /path/to/local/file username@server_address:/path/to/remote/directory

Replace /path/to/local/file with the path to the local file on the client, username with your username on the server, server_address with the IP address or hostname of the server, and /path/to/remote/directory with the path to the remote directory on the server.

SSH is a powerful tool for secure remote access and file transfer in Linux. It provides a secure channel between two devices over an unsecured network. By following the steps outlined in this article, you can easily use SSH in your Linux system for secure communication and file transfer.

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That's it for this post. Keep practicing and have fun. Leave your comments if any.