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Tools: How SSH Actually Works (Step-by-Step for Developers) - Expert Insights

2026-04-04 0 views admin
Tools: How SSH Actually Works (Step-by-Step for Developers) - Expert Insights

🚀 1. TCP Connection

🤝 2. Negotiation Phase

🔑 3. Session Key Generation

🔐 4. Authentication (Public Key)

Generate SSH key

Copy public key to server

Or manually:

✅ 5. Verification

🔄 6. Encrypted Communication

⚡ 7. Command Execution Flow

🌐 Bonus: SSH Tunneling (Port Forwarding)

Example:

🧠 Why SSH Is So Powerful

🔐 Best Practices

💭 Question Most developers use SSH every day: …but very few know what’s actually happening under the hood. Let’s break it down 👇 Everything starts with a basic TCP connection between client and server. The client and server exchange: They agree on a secure configuration before continuing. SSH uses a key exchange algorithm (e.g. Diffie-Hellman) to generate a shared session key. 👉 This session key is used for encrypting all communication. If you're using SSH keys: 👉 The server checks if your public key exists there. The server sends an encrypted challenge. The client decrypts it using its private key. 👉 If successful → authentication is complete. Now everything is encrypted using the session key: 👉 Sent encrypted → executed → returned encrypted SSH can create secure tunnels. 👉 Now you can connect to the remote DB via: Do you use password authentication or SSH keys in your setup? Templates let you quickly answer FAQs or store snippets for re-use. Are you sure you want to ? It will become hidden in your post, but will still be visible via the comment's permalink. Hide child comments as well For further actions, you may consider blocking this person and/or reporting abuse

Command

Copy

$ ssh user@server ssh user@server ssh user@server Client -------- Key Exchange -------- Server -> shared secret key <- Client -------- Key Exchange -------- Server -> shared secret key <- Client -------- Key Exchange -------- Server -> shared secret key <- ssh-keygen -t rsa -b 4096 -C "[email protected]" ssh-keygen -t rsa -b 4096 -C "[email protected]" ssh-keygen -t rsa -b 4096 -C "[email protected]" ssh-copy-id user@server ssh-copy-id user@server ssh-copy-id user@server cat ~/.ssh/id_rsa.pub cat ~/.ssh/id_rsa.pub cat ~/.ssh/id_rsa.pub ~/.ssh/authorized_keys ~/.ssh/authorized_keys ~/.ssh/authorized_keys ls -la Client -> (encrypted command) -> Server Server -> (execute command) Server -> (encrypted response) -> Client Client -> (decrypt response) Client -> (encrypted command) -> Server Server -> (execute command) Server -> (encrypted response) -> Client Client -> (decrypt response) Client -> (encrypted command) -> Server Server -> (execute command) Server -> (encrypted response) -> Client Client -> (decrypt response) ssh -L 3000:localhost:5432 user@remote-server ssh -L 3000:localhost:5432 user@remote-server ssh -L 3000:localhost:5432 user@remote-server localhost:3000 localhost:3000 localhost:3000 # Disable password authentication (server-side) PasswordAuthentication no # Disable password authentication (server-side) PasswordAuthentication no # Disable password authentication (server-side) PasswordAuthentication no # Set correct permissions chmod 700 ~/.ssh chmod 600 ~/.ssh/authorized_keys # Set correct permissions chmod 700 ~/.ssh chmod 600 ~/.ssh/authorized_keys # Set correct permissions chmod 700 ~/.ssh chmod 600 ~/.ssh/authorized_keys # Use SSH agent eval "$(ssh-agent -s)" ssh-add ~/.ssh/id_rsa # Use SSH agent eval "$(ssh-agent -s)" ssh-add ~/.ssh/id_rsa # Use SSH agent eval "$(ssh-agent -s)" ssh-add ~/.ssh/id_rsa - No encryption yet - Just a raw connection - SSH protocol versions - Supported encryption algorithms - Key exchange methods - Uses asymmetric cryptography (public/private keys) - Establishes a fast symmetric session key - Protects against eavesdropping and MITM attacks

🏷️ Tags

toolsutilitiessecurity toolsactuallyworksdevelopersexpertinsights

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