Secure Shell (SSH) Connection via Port 22

SSH is a cryptographic network protocol that enables secure communication between two networked devices. It is primarily used for remote administration, file transfers, and other network services that require a high degree of security.

Purpose:

  • Establish a secure, encrypted communication channel between two networked devices.
  • Facilitate remote command execution, file transfers, and other network services.

Components:

By default, SSH servers listen for incoming connections on TCP port 22. However, this default status can make it a target for automated attacks.

  • SSH Client: Software running on the user’s machine (e.g., ssh command in terminals).
  • SSH Server: Software running on the remote machine (e.g., sshd daemon on Linux).
  • Port 22: The default network port where the SSH server listens for incoming connections.

Connection Steps:

The client initiates an SSH connection by sending a request to the server on port 22. The server responds, and the two then negotiate a secure, encrypted channel using a key exchange mechanism. Authentication is typically performed using either password-based authentication or, preferably, public key authentication.

Client Initiation: – The client sends a request to the server on port 22. – Server responds, identifying itself (including its SSH protocol version).

Key Exchange: – Client and server negotiate a shared secret key (ephemeral session key) using cryptography. – This key encrypts all subsequent communication.

Authentication: – The client proves its identity to the server. – Password Authentication: (Less secure, vulnerable to brute-force attacks) – Public Key Authentication: (Recommended, uses key pairs for strong security)

Session Establishment: – Once authenticated, a secure, encrypted tunnel is formed. – The client can now interact with the remote system as if directly connected.

Security Considerations:

  • Port 22 as a Target: Due to its default status, Port 22 is often probed for vulnerabilities. Consider changing to a non-standard port.
  • Firewall Configuration: Ensure your firewall only allows inbound traffic from trusted sources on port 22 (or your chosen port).
  • Strong Authentication: Prioritize public key authentication over passwords.
  • Regular Updates: Keep both SSH client and server software up-to-date with security patches.

Common Uses of SSH:

  • Remote Administration: Managing servers, routers, and other network devices.
  • Secure File Transfer: Using tools like scp or sftp for encrypted file transfers.
  • Port Forwarding: Tunneling other protocols (like HTTP) through the secure SSH connection.
  • Remote Development: Editing code on remote servers directly from your local environment.

Additional Notes:

  • Non-Standard Ports: While not mandatory, using a non-standard port can deter automated attacks.
  • SSH Configuration: The /etc/ssh/sshd_config file allows extensive customization of the SSH server’s behavior.
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Richard.Bailey

Richard Bailey, a seasoned tech enthusiast, combines a passion for innovation with a knack for simplifying complex concepts. With over a decade in the industry, he's pioneered transformative solutions, blending creativity with technical prowess. An avid writer, Richard's articles resonate with readers, offering insightful perspectives that bridge the gap between technology and everyday life. His commitment to excellence and tireless pursuit of knowledge continues to inspire and shape the tech landscape.

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