What processes and protocols are involved at the operating system and network level when establishing an SSH connection?

The following processes and protocols are involved in establishing an SSH connection:

1. TCP/IP — a TCP connection is established with the server on port 22 (default) at the network level.
2. SSH protocol — data exchange occurs over the SSH protocol (Secure Shell) on top of TCP, which provides a secure encrypted connection.

Main stages:

• Establishing a TCP connection (3-way handshake).
• Key exchange: the client and server agree on encryption parameters, exchanging public keys to create a secure channel.
• Authentication: the client proves its identity (password, keys, certificates).
• Establishing a secure channel: all subsequent traffic is encrypted.

Thus, SSH uses TCP for transport, and implements encryption, authentication, and session management at the protocol level.