SSH Under the Hood

• Secure Shell (SSH) creates an encrypted channel between client and server.
• The process begins with a TCP connection, followed by version negotiation.
• Both parties then agree on encryption algorithms, key exchange methods, and message authentication codes.
• The client and server perform a key exchange (typically using Diffie-Hellman) to securely generate a shared session key for encrypting the connection.
• For authentication, SSH commonly uses public key authentication.
• The server verifies the client’s identity through a challenge-response mechanism using the client’s public key, without the private key ever being transmitted.
• Once authenticated, the session key encrypts all further communication, providing a secure channel.