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What is SSH (Secure Shell)? - (BCA / B.Tech)

What is SSH (Secure Shell)?

SSH (Secure Shell) is a cryptographic network protocol used for secure communication over an insecure network. Its main use is for remote login and to securely access network services. SSH allows you to securely communicate with and manage a computer or server on a network. It is a medium that ensures secure communication with data encryption on an insecure network. The main purpose of SSH is to secure data and protect the user's sensitive information, such as passwords, commands, and files, so that no middleman (attacker) can see or change the data. SSH is a powerful and secure network protocol that secures services like remote server management, file transfer, and network tunneling. Its encryption and authentication capabilities make it highly reliable for modern network communication.

Main Components of SSH:

SSH has three main components:

Transport Layer: This layer establishes a secure and encrypted connection between the client and the server. It ensures data integrity and encryption to keep the data safe from tampering or fraud.
Authentication Layer: In this layer, the identity of the user or host is confirmed. In SSH, the client's identity is authenticated using techniques like passwords or public-private keys (RSA, DSA, ECDSA).
Connection Layer: This layer supports multiple channels during an SSH session. In SSH, data can be sent through multiple channels on a single connection, which makes data transfer and communication easy and efficient.

Uses of SSH:

SSH is used for various purposes, which mainly include the following:

Remote Login: The main use of SSH is to log in to a remote server. You can control another computer (or server) from one computer, even if it is in any corner of the world.
Command Execution: SSH can be used to securely execute commands on a remote server.
File Transfer: The SSH protocol can also be used for file transfer. SCP (Secure Copy Protocol) and SFTP (SSH File Transfer Protocol) are part of SSH, which provide the facility to transfer files securely.
Tunneling or Port Forwarding: SSH is also used to secure network traffic. Using SSH tunneling, we can securely pass data over an insecure network.
Use as VPN: SSH can also be used as a type of simple VPN. It creates an encrypted channel to secure network traffic and protects against unauthorized access.

Security Features of SSH:

Encryption: SSH uses encryption, which secures the data.
Authentication: SSH has several ways to confirm the identity of the user and host, including passwords, public key authentication, and multi-factor authentication.
Integrity: SSH ensures that no changes have been made during data transfer.
Secure Communication: The SSH protocol guarantees secure communication.

Main Algorithms of SSH:

The following algorithms are used in SSH:

Symmetric Encryption: For data encryption, symmetric encryption algorithms like AES, Blowfish, and 3DES are used in SSH.
Asymmetric Encryption: SSH uses a public-private key pair. RSA, DSA, and ECDSA are prominent in this type of encryption.
Hashing: For message authentication, hashing algorithms like MD5 and SHA-2 are used in SSH.

Comparison of SSH and Other Protocols:

SSH vs Telnet: Both SSH and Telnet are used for remote login, but SSH is more secure because it is encrypted, while in Telnet, data is sent in plaintext, which makes it easy to intercept.
SSH vs FTP: FTP is an insecure protocol used for file transfer, while SFTP or SCP protocols based on SSH are secure and send data by encrypting it.

Advantages of SSH:

Secure Connection: SSH establishes a secure connection on the network, which keeps the user's data and communication safe.
Multiplexing: SSH can handle multiple channels on a single connection, which allows multiple tasks to be performed at the same time.
Diversity: SSH secures various types of services such as remote login, file transfer, and network traffic proxy.
Exceptional Security: SSH has public-private key-based authentication, which makes it more secure than password-based security.

Disadvantages of SSH:

Not Convenient: Setting up and configuring SSH can be a bit complex, especially for new users.
Need for Correct Key: SSH depends on public-private key security, so if the key is incorrect or lost, recovery can be difficult.
Server Security: If there are vulnerabilities in the server, an attacker can gain access to the server through SSH.

What is SSH (Secure Shell)?

What is SSH (Secure Shell)?

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