# Run OpenAI Codex CLI on a remote machine

> Start a cloud VM where Codex CLI is already installed, sign in with codex login --device-auth or an API key, and run codex or codex exec there. On Sandboxer, sbx new gives you that VM in seconds, and you can also send Codex tasks from your laptop with sbx prompt --provider codex.

Source: https://sandboxer.com/guides/run-codex-cli-on-a-remote-machine. Updated 2026-10-24.

**Short answer:** Start a cloud VM where Codex CLI is already installed, sign in with codex login --device-auth or an API key, and run codex or codex exec there. On Sandboxer, sbx new gives you that VM in seconds, and you can also send Codex tasks from your laptop with sbx prompt --provider codex.

## At a glance

| Topic | Detail |
| - | - |
| Codex CLI | Preinstalled in every sandbox (codex-cli 0.163.0 when we checked) |
| Sign-in options (OpenAI's docs) | Device code, API key, copy `~/.codex/auth.json`, or forward the login callback on port 1455 |
| Unattended runs | `codex exec "…"`, read-only by default; add `--sandbox workspace-write` to allow edits |
| From your laptop | `sbx prompt <id> --provider codex "…"` with your OpenAI key on the dashboard's **Agents** page |
| Machine | `default`: 4 vCPU, 8 GB RAM, 50 GB disk, $0.036/hour, billed per second, free while stopped |

## 1. Create the VM

```bash
curl -fsSL https://sandboxer.com/install | sh    # installs sbx and signs you in
sbx new
sbx exec sb_k3v9x2mq "codex --version"
```

## 2. Sign in to Codex on the VM

OpenAI's [authentication docs](https://learn.chatgpt.com/docs/auth) list these methods for remote and headless machines. Pick one.

**Device code (OpenAI's preferred method for headless machines; beta).** First enable device code login in your ChatGPT security settings, or ask your workspace admin to. Then:

```bash
sbx ssh sb_k3v9x2mq
codex login --device-auth      # open the link on your laptop and enter the code
```

**API key**, for scripts and CI:

```bash
sbx ssh sb_k3v9x2mq -- bash -lc 'printenv OPENAI_API_KEY | codex login --with-api-key'
```

This needs `OPENAI_API_KEY` set inside the VM, for example with `sbx new -e OPENAI_API_KEY="$OPENAI_API_KEY"`.

**Copy your existing login.** If you've already run `codex login` on your laptop, copy the auth cache. OpenAI's docs say to treat this file like a password, because it contains access tokens.

```bash
sbx exec sb_k3v9x2mq "mkdir -p ~/.codex"
sbx scp ~/.codex/auth.json sb_k3v9x2mq:/home/user/.codex/auth.json
```

**Forward the login callback.** Codex's browser login calls back to `localhost:1455`. Forward that port from your laptop to the VM, then run `codex login` in the VM and open the printed address on your laptop:

```bash
sbx forward sb_k3v9x2mq --remote 1455 --local 1455   # stays open until Ctrl+C; use a second terminal for codex login
```

## 3. Run it

Interactively, in a `tmux` session so it survives a dropped connection:

```bash
sbx ssh sb_k3v9x2mq
tmux new -s codex
codex
```

Unattended, with `codex exec`. It prints progress to stderr and only the final message to stdout. It's read-only unless you allow edits:

```bash
sbx exec sb_k3v9x2mq --detach --cwd my-repo \
  "codex exec --sandbox workspace-write 'Fix the failing tests and commit on a branch'"
```

OpenAI's docs say to use `--sandbox danger-full-access` "only in a controlled environment (for example, an isolated CI runner or container)". A sandbox VM started with `--no-env` and only the key it needs is that kind of environment. If you copied your `auth.json` in, remember the agent can read those tokens too; prefer a dedicated API key there.

## 4. Or drive it from your laptop

Add your OpenAI key on the dashboard's **Agents** page once. Then send Codex tasks without opening a shell, and follow its events:

```bash
sbx prompt sb_k3v9x2mq --provider codex "Refactor the auth module and add tests"
sbx events sb_k3v9x2mq --follow
```

## Keep it running, or pause it

```bash
sbx extend sb_k3v9x2mq --hours 12    # a new sandbox auto-stops after 1 hour
sbx stop sb_k3v9x2mq                 # saves memory and disk; free while stopped
sbx resume sb_k3v9x2mq               # the tmux session and codex are still running
```

## FAQ

### How do I log in to Codex CLI over SSH?

Use `codex login --device-auth`, which OpenAI recommends for headless machines. The alternatives are an API key (`printenv OPENAI_API_KEY | codex login --with-api-key`), copying `~/.codex/auth.json`, or forwarding port 1455 for the browser callback.

### Can I use my ChatGPT plan instead of an API key?

Yes, when you sign in yourself on the VM with device code, the copied auth cache or the forwarded callback. For `sbx prompt`, add an OpenAI API key on the dashboard's **Agents** page.

### Does codex exec change files by default?

No. OpenAI's docs say `codex exec` runs in a read-only sandbox by default. Pass `--sandbox workspace-write` to let it edit files.

### Is --full-auto still supported?

No. OpenAI's docs say `--full-auto` is no longer supported, and point to `--sandbox workspace-write` instead.

### What does the VM cost?

The `default` size is $0.036 an hour, billed per second, and nothing while stopped. OpenAI bills model usage separately.