Setting up your spare Mac for Claude Code to control, a step-by-step guide

TL;DR Highlight

Setting up a spare Mac with SSH and tmux gives Claude Code an isolated machine you can drive from your phone.

Who Should Read

A Mac-using developer who wants to run agents with --dangerously-skip-permissions but doesn't trust their main machine.

Core Mechanics

Isolate the agent on a spare Mac
- Create a fresh local account with no Apple ID and no personal data.
- With nothing sensitive to reach, giving broad permissions is less risky.
Containers weren't enough
- A container still runs on your main machine, and its network requests go through it.
- Mac-only apps like Unity can't run in one, so computer use can't control them either.
SSH and sleep prevention are the backbone
- Enable Remote Login and connect with an ed25519 key. The guide recommends a .local hostname over an IP.
- Use pmset to disable sleep and stop the screen saver from locking.
Computer use doesn't work over plain SSH
- macOS ties Screen Recording and Accessibility permissions to the GUI login session, so SSH processes can't reach the display.
- A LaunchAgent keeps a tmux server alive inside the GUI session, and claude sessions started there inherit access.

Community Reactions

A VM with libvirt is enough, one commenter argued
- They see no reason for real hardware isolation outside graphics development.
- They give Claude root and a desktop for Chrome UAT, and reinstall in seconds if it breaks things.
Connection drops reported by someone running the same setup
- They used it as a free replacement for an OpenClaw bot.
- It sometimes loses its connection and the phone handoff must be redone.
The isolated box still has network access, commenters warned
- It's cut off from your files but can still reach other devices on the network.
- Several suggest a separate VLAN or deny-all firewall rules.
Giving sudo to an agent is reckless, one commenter said
- They give Claude an unprivileged UNIX account only.
- They don't bother with containers or VMs.
Alternative setups shared by commenters

How to Apply

Audit your agent machine's isolation
- Within 30 minutes, list the personal data, Apple ID and logged-in accounts on the machine your agent runs on.
- If you have a spare Mac, create a fresh local account without an Apple ID.
Set up SSH keys and sleep prevention first
- On the target, run sudo systemsetup -setremotelogin on, then ssh-keygen and ssh-copy-id as in the guide.
- Run sudo pmset -c sleep 0 and verify you can ssh in.
Put the box on a separate VLAN or behind a firewall
- Move it to a guest network or VLAN on your router.
- Block access to internal devices and allow only internet.
Grant tmux permissions and restart the server for computer use
- Run setup-computer-use.sh, then enable Screen Recording and Accessibility for tmux at the machine.
- Run tmux -S /tmp/cc-tmux.sock kill-server and confirm it works in a new session.

Try It

copy & run

# Run in the target Mac's terminal (or over SSH). Summary of steps 3 and 6. {{user}} is the target account name

echo "{{user}} ALL=(ALL) NOPASSWD: ALL" | sudo tee /etc/sudoers.d/{{user}}-nopasswd >/dev/null
sudo chmod 440 /etc/sudoers.d/{{user}}-nopasswd
sudo visudo -cf /etc/sudoers.d/{{user}}-nopasswd   # must print 'parsed OK'
sudo -n true && echo ok

sudo pmset -c sleep 0
sudo pmset -c disablesleep 1
sudo pmset -c displaysleep 0
pmset -g | grep -iE 'sleep'

# Next: on your main Mac run ssh-keygen -t ed25519, then ssh-copy-id {{user}}@{{hostname}}.local, then ssh {{user}}@{{hostname}}.local whoami

Terminology

--dangerously-skip-permissionsA Claude Code flag that runs actions without asking for approval each time. Convenient, but risky enough that you want an isolated machine.

computer useClaude takes screenshots and controls the mouse and keyboard directly. It does what a person sitting at the computer would do.

tmuxA tool that keeps terminal sessions alive like a server so you can reattach later. Here it runs inside the GUI session so SSH-attached sessions get display permissions.

LaunchAgentA macOS mechanism that starts a program inside a login session and restarts it if it dies. Similar to a systemd user service on Linux.

Remote ControlA feature that lets you drive a running Claude Code session from the Claude phone app. Start it with /remote-control or claude remote-control.