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ariana-dot-devariana-dot-dev/cloud-sandbox-vm-skills/skills/expose-localhost-tunnel/SKILL.md

expose-localhost-tunnel

Skill2 starsChanged 5 months agoMITView on GitHub

Tunnel/expose a localhost service to the internet from inside a cloud VM — get a stable public HTTPS URL (https://<box>-<port>.on.ascii.dev) with TLS and token-gating built in, no separate daemon or account like ngrok. The VM's dedicated IPv4 also allows raw TCP/UDP and bring-your-own domain. Use to share a preview, expose a webhook target, or open a port.

  • Pipes a download into a shell
  • Reads credentials

The file

We split this skill into the rules it gives an agent

2 rules. About 0 are common, 2 are distinctive, and 0 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈2

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 0

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Use this when a service running in a Box must be reachable from outside: sharing a dev preview, receiving webhooks, or demoing.

    line 8
  2. Distinctive:

    No separate daemon/account — the route lives with the VM.

    line 23

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Expose / tunnel localhost (Box)

Use this when a service running in a Box must be reachable from outside: sharing a dev preview, receiving webhooks, or demoing. Because the service already runs inside the VM, exposing it is one command — no ngrok-style sidecar, no extra account, no cert setup.

Recipe

box ssh "$box_id" -- "cd /app && PORT=3000 npm start &"   # MUST bind 0.0.0.0
box ssh "$box_id" -- "host 3000 --title preview"
box ssh "$box_id" -- "host url 3000"                       # -> https://<box>-3000.on.ascii.dev?_token=...
box ssh "$box_id" -- "host list"                           # manage; host hide <port> to revoke

Ascii terminates TLS for on.ascii.dev and proxies to the box. URLs are token-gated by default (--public drops the token, --private enforces it).

Why Box beats a tunnel tool

  • No separate daemon/account — the route lives with the VM.
  • TLS + auth handled; URL stable across the box's life.
  • Dedicated IPv4 + full TCP/UDP — non-HTTP servers and BYO domains work; most sandbox providers can't tunnel raw TCP/UDP at all.

Prereqs

curl -fsSL https://box.ascii.dev/install | sh, then box login "$BOX_API_KEY" --json.

Gotchas

App must bind 0.0.0.0. For a URL that outlives a long session, pair with box extend <id> --no-auto-stop. EU-only region today.

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