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A Deep Dive into How SSH Works: Step-by-Step Guide
If you’ve ever needed to remotely access or manage a server, chances are you’ve used SSH (Secure Shell). SSH is the go-to protocol for securely connecting to machines over a network, allowing for encrypted communication and authenticated access. While it’s a tool many of us use daily, understanding the nitty-gritty of how SSH actually works can deepen your appreciation of this powerful protocol. Let’s break it down step by step, based on the detailed flow of the SSH process.
1. Kicking Things Off: Connection Initialization
The SSH journey begins when the client reaches out to the server. This happens over port 22, the default port for SSH. As soon as the connection request hits, the server responds by sending over its SSH protocol version along with a menu of supported cryptographic algorithms. These algorithms cover encryption, MAC (Message Authentication Code), compression, and key exchange — essentially laying out the tools that will keep your session secure.
- Client’s Move: Initiates the TCP connection on port 22.
- Server’s Response: Sends back the protocol version and supported algorithms.
