Run a Rex server on a remote Linux VM

Set up the VM#

On your computer, create a VM and connect to it. Pick any free name; if you've already clicked Deploy or have a VM, skip the first command and use its name:

ssh exe.dev new --name=my-rex
ssh my-rex.exe.xyz

On the VM, connect Claude Code and Codex to the LLM integration, then install Rex with Superlogical's install script. It adds Rex's apt repository, so updates come with apt. There's no stable release yet, so ask for the preview channel, the tagged builds:

exeuntu configure claude
exeuntu configure codex
curl -fsSL https://pkgs.superlogical.com/rex/install.sh | sh -s -- --channel preview
rex version

The package brings services for a shared server and a login server; leave them off. Instead, run a personal server as exedev, the account with your files and agents, and let it join your tailnet as my-rex with the Tailscale built into Rex. The second file stops Ubuntu's needrestart from restarting it during package upgrades, which would stop every program running in Rex:

sudo tee /etc/systemd/system/rex-personal.service >/dev/null <<EOF
[Unit]
Description=Rex server for $USER, on the tailnet as $(hostname)
Wants=network-online.target
After=network-online.target user@$(id -u).service

[Service]
Type=notify
NotifyAccess=main
User=$USER
Environment=XDG_RUNTIME_DIR=/run/user/$(id -u)
Environment=GODEBUG=
ExecStart=/usr/bin/rex server run --log-format text --tailscale --tailscale-hostname $(hostname)
Restart=on-failure
RestartSec=5s

[Install]
WantedBy=multi-user.target
EOF
echo '$nrconf{override_rc}{qr(^rex-personal\.service$)} = 0;' | sudo tee /etc/needrestart/conf.d/rex-personal.conf
sudo systemctl daemon-reload
sudo systemctl enable --now rex-personal.service

Install Rex's skill and hooks for the agents, so they can open tabs, split panes and read other terminals, and make a project, a Git repository so you can review and undo what the agents change. Then open a session there:

rex skill setup
git init ~/project
rex new work -c ~/project

Check it. The service is active, the server is the preview build, and Claude Code, typed into the work session, answers OK on its screen:

systemctl is-active rex-personal
rex server status | grep -E '^(version|tailscale)'
rex send -s work 'claude -p --model haiku "Reply with exactly: OK"'
rex send-key -s work Enter
sleep 20; rex capture -s work | tail -3

tailscale: needs login is expected until the next step.

Sign in to Tailscale#

Rex for Mac reaches the server over your tailnet. You need a Tailscale account, with the Tailscale app on your Mac, and two settings on in the admin console: MagicDNS and HTTPS Certificates.

On the VM, print the server's sign-in link:

rex server status

Open the authenticate: link in a browser where you're signed in to Tailscale, and approve the device. It joins your tailnet as my-rex, owned by you, and from then on the server signs itself in after restarts. Run rex server status again: the tailscale: line no longer says needs login.

Only devices signed in as you get in; the server asks Tailscale who each caller is. To let other people in, see Rex's Who Can Connect. The server's sign-in counts as a device on your tailnet, and Tailscale expires device keys after 180 days unless you turn off key expiry for my-rex.

Add it to Rex for Mac#

In Rex for Mac, choose Add Remote Host… and enter the server's address, with your tailnet's name:

https://my-rex.<your-tailnet>.ts.net

The work session from setup is there. Open it, or start a new one, and run an agent in ~/project:

cd ~/project && claude

The first run asks for a theme and whether you trust the folder. Then give it a task, such as:

Write index.html: a one-page site for a very opinionated cat. Keep it short.

Close the laptop; the agent carries on, and the session is as you left it when you reattach. Codex works the same way (codex); the first time, approve Rex's hook with /hooks so Codex knows it runs in Rex.

The rex command works from a terminal on your Mac too, and inside Rex terminals there:

rex hosts add my-rex https://my-rex.<your-tailnet>.ts.net
rex -S my-rex ls

Let agents drive Rex#

rex skill setup taught Claude Code and Codex the rex commands. Ask an agent running in Rex to "start the dev server in another tab and tell me when it's ready" or "run the tests beside you and fix whatever fails", and you watch it happen in the window. Rex lists more in its agent docs. Run rex skill setup again after installing another agent.

Shelley, exe.dev's own agent at https://my-rex.shelley.exe.xyz/, picks up the same skill: ask it to open a session in Rex and run something, and it shows up in Rex for Mac.

To preview what an agent builds, have it serve on 0.0.0.0:8000 and open https://my-rex.exe.xyz/, private until you share it.

No Tailscale? Use an SSH tunnel#

The server's own socket on the VM is /run/user/1000/rex/server.sock, and Rex trusts whoever connects there as exedev. SSH can carry that socket to your computer, protected by your exe.dev SSH key. On your Mac, keep this running:

ssh -N -L /tmp/rex-my-rex.sock:/run/user/1000/rex/server.sock my-rex.exe.xyz

Then, in another terminal:

rex -S unix:///tmp/rex-my-rex.sock ls

We tested this with the rex command. We couldn't test whether Rex for Mac's Add Remote Host… takes a socket address; Rex's docs only describe Tailscale for the app. The tunnel ends when SSH does, and the socket file stays behind: delete /tmp/rex-my-rex.sock before you open it again.

What keeps running#

• Mac asleep, Rex closed, Wi-Fi gone: everything on the VM keeps running.
• The VM restarts: the server comes back on its own with the same sessions, tabs and panes, each a fresh shell in the same folder. Programs that were running in them have stopped.
• Rex updates: apt installs the new version but leaves the running server alone. It switches when you restart it (see Update).

Back up and restore#

Commit and push your code; that's the copy that matters most. For a copy of the whole VM, run this on your computer (choose a free backup name):

ssh exe.dev cp my-rex my-rex-backup

The copy has the original's Tailscale identity too, so don't keep both running. To use the copy beside the original, give it its own on the copy, then open the new link from rex server status:

sudo systemctl stop rex-personal
rm -rf ~/.local/state/rex/tsnet
sudo sed -i "s/--tailscale-hostname .*/--tailscale-hostname $(hostname)/" /etc/systemd/system/rex-personal.service
sudo systemctl daemon-reload && sudo systemctl start rex-personal

Update#

On the VM:

sudo apt-get update && sudo apt-get install --only-upgrade rex
rex version | head -1
rex server status | grep '^version'

If the two versions differ, the server is still on the old one. When nothing important is running in Rex, restart it; sessions come back as in a reboot:

sudo systemctl restart rex-personal

Rex for Mac and the server don't need the same version; if they drift too far apart, the connection error says which one to update. Update the agents with sudo exeuntu update claude and sudo exeuntu update codex.

Troubleshooting#

• Rex for Mac can't reach the server. On the VM, rex server status should show Tailscale signed in. Check that your Mac's Tailscale app is connected to the same tailnet, that MagicDNS and HTTPS certificates are on, and that the device is named my-rex in the admin console (Tailscale adds a number if the name was taken).
• Rex for Mac is refused. Only Tailscale devices signed in as the server's owner get in. rex client ls on the VM shows who is connected.
• rex says (R)?ex. Ubuntu has an unrelated Perl tool called rex; run the install script again, and see apt-cache policy rex.
• The server won't start. journalctl -u rex-personal -e shows why. rex server status prints the path of the server's own log.
• An agent doesn't answer. On the VM, claude -p "Reply with exactly: OK" shows whether Claude Code works on its own; rerun exeuntu configure claude if not, then rex skill setup.

For everything else, see Rex's Linux server docs and Remote Access.