Introduction To SSH:

SSH (Secure Shell) is a network protocol that provides a secure way to access and manage remote devices or servers over an unsecured network. Developed as a replacement for insecure protocols like Telnet and rlogin, SSH encrypts data transmitted between the client and server, ensuring confidentiality and integrity.

Here’s an introduction to SSH and its key features:

1. Secure Communication: SSH encrypts data exchanged between the client and server, including authentication credentials, commands, and data transfers. This encryption prevents eavesdropping and data tampering by unauthorized parties.
2. Authentication: SSH uses cryptographic techniques for user authentication, ensuring that only authorized users can access the remote device or server. It supports various authentication methods, including password-based authentication, public key authentication, and multi-factor authentication.
3. Key Exchange: During the SSH handshake, the client and server exchange cryptographic keys to establish a secure connection. This key exchange process ensures that both parties can securely communicate without the risk of interception or tampering.
4. Port Forwarding: SSH supports port forwarding, allowing users to securely tunnel network connections between the client and server. This feature enables secure access to services running on remote servers, such as web servers, databases, and other networked applications.
5. Remote Administration: SSH provides a command-line interface (CLI) for remotely managing and administering devices or servers. Users can execute commands, transfer files, and perform administrative tasks on remote systems securely and efficiently.
6. Tunneling and Proxying: SSH can be used for tunneling and proxying network connections, enabling secure access to internal resources from external networks. This capability is particularly useful for remote access to corporate networks or accessing restricted services over the internet.

Overall, SSH is a fundamental tool for secure remote access and administration in various computing environments, including system administration, software development, and network management. Its robust security features and versatility make it a widely adopted protocol for securely managing remote systems and services.

SSH Tunnels:

SSH tunnels allow secure communication between a local and remote machine by forwarding network connections. They come in three types: local port forwarding, remote port forwarding, and dynamic port forwarding, enabling access to remote services and bypassing network restrictions.

Shell and Command Tunnels:

Shell and command tunnels, facilitated by SSH, create secure channels for remote shell access and execution of commands between local and remote machines, enhancing security and enabling remote management.

a. port forwarding tunnels:

This type of tunnels was designed to provide secured tunneling for third party applications. the idea behind port forwarding is described below from the client’s point of view:

1. Local Port Forwarding: Local port forwarding is a feature of SSH that allows you to securely forward traffic from a local port on your machine to a specific destination reachable from a remote server, facilitating access to remote services from your local machine.
2. Remote Port Forwarding: Remote port forwarding is an SSH feature that securely forwards traffic from a port on the remote server to a destination reachable from your local machine, enabling access to services running on your local machine from the remote server or other machines on the remote network.

b. Custom tunnels:

Custom tunnels, often facilitated by SSH, are tailored network connections that enable secure communication between local and remote systems based on specific requirements. These tunnels can be configured to route traffic through intermediate servers, implement specific encryption methods, or traverse firewalls, providing flexible and customized solutions for secure network communication.

SFTP:

SFTP (SSH File Transfer Protocol) is a secure file transfer protocol that provides secure file access, transfer, and management over an SSH-encrypted connection. It allows users to securely upload, download, and manage files on remote servers.