Tailscale

Tailscale provides a WireGuard-based mesh VPN connecting MEGATRON to other machines in the network. It enables secure, direct SSH access and inter-machine communication without exposing ports to the internet.

Tailscale Mesh

Machine	Hostname	Tailscale IP	Role	Hardware
MEGATRON	megatron	100.70.25.47	Primary server, K3s control plane	Threadripper 3990X, 251GB, 2x RTX 3090
Mac Studio	lucass-mac-studio	100.87.201.64	Inference, visualization, large models	M2 Ultra, 512GB unified, 7.3TB
MacBook M4	macbook-pro-m4	100.91.253.88	Development, quick tests	M4 Max, 64GB
Lambda Laptop	tensorbook	100.108.49.109	Ablations, single-GPU experiments	1x RTX GPU, 64GB

Network Diagram

                    ┌─────────────────────┐
                    │     Tailscale       │
                    │   Coordination      │
                    │     Server          │
                    └─────────┬───────────┘
                              │ (control plane only,
                              │  data flows peer-to-peer)
         ┌────────────────────┼────────────────────┐
         │                    │                    │
         v                    v                    v
┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐
│    MEGATRON     │ │   Mac Studio    │ │  MacBook M4     │
│  100.70.25.47   │ │ 100.87.201.64   │ │ 100.91.253.88   │
│                 │ │                 │ │                 │
│  K3s cluster    │<────────────────>│  Development    │
│  GPU training   │ │  Inference      │ │  Quick tests    │
│  Prod hosting   │ │  Visualization  │ │                 │
└────────┬────────┘ │  Large models   │ └─────────────────┘
         │          └─────────────────┘
         │
         v
┌─────────────────┐
│  Lambda Laptop  │
│ 100.108.49.109  │
│                 │
│  Ablations      │
│  Single-GPU     │
└─────────────────┘

SSH via Tailscale

SSH config entries for Tailscale-based access (from ~/.ssh/config):

SSH Alias	Target	IP	Notes
mac-studio	Mac Studio M2 Ultra	100.87.201.64	Also available as mac-studio-local (10.0.0.71 LAN)
macbook-m4	MacBook M4 Max	100.91.253.88
tensorbook	Lambda Laptop	100.108.49.109
megatron-rescue	MEGATRON rescue SSH	localhost:2222	High-priority access

# SSH to Mac Studio via Tailscale
ssh mac-studio

# SSH to MacBook
ssh macbook-m4

# SSH to Lambda
ssh tensorbook

Use Cases

Research Workload Distribution

Machine	Use For
MEGATRON	Full training runs, distributed (multi-GPU) experiments
Mac Studio	Inference, visualization, loading large models (512GB memory)
MacBook M4	Development, quick iteration, code editing
Lambda	Single-GPU ablations, smaller experiments

Data Transfer

# Copy dataset from MEGATRON to Mac Studio
scp -r /mnt/shared/datasets/cifar10 mac-studio:~/datasets/

# Rsync checkpoints
rsync -avz /mnt/shared/checkpoints/rosa/ mac-studio:~/checkpoints/rosa/

# Copy results back
scp mac-studio:~/results/inference.json /mnt/shared/results/

Tailscale Management

# Check Tailscale status
tailscale status

# Check connection to a specific peer
tailscale ping mac-studio

# View Tailscale IP
tailscale ip

# Check network diagnostics
tailscale netcheck

# Enable/disable Tailscale
sudo tailscale up
sudo tailscale down

Tailscale on K3s

Tailscale runs as a system service (tailscaled.service) and provides an overlay network independent of the K3s cluster network. Pods within K3s do not use Tailscale directly -- Tailscale is used for machine-to-machine communication and SSH access.

MEGATRON Infrastructure Documentation