As Internet access becomes increasingly inexpensive and available, it has become a viable replacement for traditional couriers, telephone, and fax, as well as remote dial-up access to a company’s internal computer resources. SSH, the Secure Shell could be a common software based approach to network security. It is a protocol that enables user to log into another computer over a network, to execute commands in a remote machine, and to maneuver files from one machine to a different.
Overview of Secure Shell
SSH or Secure Shell is a network communication protocol that enables two computers to communicate and share data. An inherent feature of SSH is that the communication between the two computers is encrypted meaning that it is suitable for use on insecure networks.
Secure Shell is a protocol that provides authentication, encryption and data integrity to secure network communications. Implementations of Secure Shell offer the following capabilities: a secure command-shell, secure file transfer, and remote access to a variety of TCP/IP applications via a secure tunnel. Secure Shell client and server applications are widely available for most popular operating systems.
SSH (Secure Shell) is a protocol for running secure network services over an insecure network. The protocol serves as the basis for many implementations of SSH that are now widely available as commercial or noncommercial products.
Typical Uses of the SSH Protocol
The protocol is used in corporate networks for:
- providing secure access for users and automated processes
- interactive and automated file transfers
- issuing remote commands
- Managing network infrastructure and other mission-critical system components.
How Does the SSH Protocol Work
The protocol works in the client-server model, which means that the connection is established by the SSH client connecting to the SSH server. The SSH client drives the connection setup process and uses public key cryptography to verify the identity of the SSH server. After the setup phase the SSH protocol uses strong symmetric encryption and hashing algorithms to ensure the privacy and integrity of the data that is exchanged between the client and server.
The figure below presents a simplified setup flow of a secure shell connection.
Figure: SSH Working
Security Benefits of Secure Shell (SSH)
The Secure Shell protocol provides four basic security benefits:
- User Authentication
- Host Authentication
- Data Encryption
- Data Integrity
User Authentication: Authentication, conjointly remarked as user identity, is the suggests that by that a system verifies that access is merely given to meant users and denied to anyone else. Several authentication strategies square measure currently used, starting from acquired type written passwords to a lot of strong security mechanisms.
Host Authentication: a host keys utilized by a server to prove its identity to a shopper and by a shopper to verify a “known” host. Host keys are represented as persistent asymmetric—much just like the public/private key pairs mentioned on top of within the Public key section.
Data Encryption: Encryption, typically stated as privacy, means that your information is shield from revelation to a would-be assaulter “sniffing” or eaves dropping on the wire. Ciphers are the mechanism by that Secure Shell encrypts and decrypts information being sent over the wire. A block cipher is that the most typical the most typical sort of stellate key algorithms.
Data Integrity: Data integrity guarantees that data sent from one end of a transaction arrives unaltered at the other end. Even with Secure Shell encryption, the data being sent over the network could still be vulnerable to someone inserting unwanted data into the data stream.
 G. Michael and R. Karthikeyan, “A Research on Secure Shell (SSH) Protocol”, International Journal of Pure and Applied Mathematics, Volume 116 No. 16 2017, pp. 559-564
 “An Overview of the Secure Shell (SSH)”, available online at: https://www.vandyke.com/solutions/ssh_overview/ssh_overview.pdf
 “SSH Protocol”, available online at: https://www.ssh.com/ssh/protocol/
 “What is SSH and how do I use it?” available online at: http://www.ucl.ac.uk/isd/services/research-it/research-data/storage/access-guide/what-is-ssh