Carlos Mavros

Remote Access & Secure Collaboration

Course 25 min read

Real compute doesn't live on your laptop. HPC clusters, cloud GPU instances — all accessed via SSH.

What Is SSH?

SSH (Secure Shell) gives you a secure, encrypted terminal session on a remote machine. Every engineer needs it.

ssh alice@192.168.1.50
ssh alice@cluster.university.edu
ssh alice@10.0.0.5 -p 2222
exit

SSH Key Authentication

Step 1: Generate a key pair:

ssh-keygen -t ed25519 -C "alice@mylaptop"

This creates ~/.ssh/id_ed25519 (private — never share) and ~/.ssh/id_ed25519.pub (public — goes on servers).

Step 2: Copy the public key to the server:

ssh-copy-id alice@192.168.1.50

Step 3: Connect without a password. SSH will use your key pair automatically.

Warning: Protect your private key. Run chmod 600 ~/.ssh/id_ed25519 to ensure only you can read it. Never share it, never copy it to servers.

SSH Config (~/.ssh/config)

Instead of typing long SSH commands every time, define aliases in your config file:

Host myserver
    HostName 192.168.1.50
    User alice
    IdentityFile ~/.ssh/id_ed25519

Host cluster
    HostName hpc.university.edu
    User a.chen
    ForwardAgent yes

Host gpu-box
    HostName 10.0.0.15
    User ubuntu
    Port 2222

Then simply:

ssh myserver

Key takeaway: Set up SSH config for every machine you connect to regularly. It saves time and reduces errors.

Transferring Files

scp

scp copies files over SSH — simple and works everywhere:

scp results.csv alice@myserver:~/data/
scp alice@myserver:~/output/sim.log ./
scp -r ./results/ alice@myserver:~/project/

rsync (smarter)

rsync is the better choice for most transfers — it only sends what changed:

rsync -av ./results/ alice@myserver:~/project/results/
rsync -av --progress ./big-dataset/ alice@myserver:~/data/
rsync -av --delete ./local-dir/ alice@myserver:~/remote-dir/

Tip: Use rsync for anything larger than a few files. It's resumable, incremental, and faster than scp for repeated transfers.

Basic Networking

A handful of networking commands you'll use constantly:

ping google.com
curl https://api.example.com
wget https://example.com/file.zip
ss -tlnp
ip addr

Remote Development with VS Code

The VS Code Remote-SSH extension lets you edit files on a remote machine as if they were local:

  1. Install the Remote-SSH extension in VS Code.
  2. Press Ctrl+Shift+P and select Remote-SSH: Connect to Host.
  3. Type your SSH config alias (e.g., myserver).

Tip: Best of both worlds — a modern GUI editor with the power of a Linux server. Your code runs on the remote machine, but you edit it locally.

Try It Yourself

Set up passwordless SSH access and a config shortcut.

Option A (real server):

  1. Generate an SSH key pair with ssh-keygen -t ed25519.
  2. Copy it to the server with ssh-copy-id user@server.
  3. Add a config entry in ~/.ssh/config.
  4. Connect using your alias: ssh myalias.

Option B (GitHub):

  1. Generate an SSH key pair with ssh-keygen -t ed25519.
  2. Add the public key to your GitHub account under Settings → SSH and GPG keys.
  3. Test the connection: ssh -T git@github.com.

Quick Quiz

Where does the public key go, and where does the private key stay?

Answer

C) The public key goes on the server in ~/.ssh/authorized_keys; the private key stays on your local machine and is never shared.