# `porthole` — Spec v0.2 Named, managed SSH port forwards. Wraps `ssh -L/-R/-D` so forwards are addressable by name instead of by PID, terminal tab, or shell history. --- ## 1. Overview **Problem:** SSH forwards are anonymous and ephemeral. They die when a terminal closes, when a laptop sleeps, or when a network blips — silently, with no notification. There's no built-in way to list what's currently forwarded, and multi-hop / reverse forwards have enough flag surface that people end up hand-rolling shell aliases per-tunnel. **Solution:** Persist forward definitions as named profiles. Run forwards as a supervised background process (not tied to a shell session), with auto-reconnect, health status, and a single command to see everything that's open. **Non-goals:** Not a replacement for a VPN or a full SOCKS/proxy manager. Not a secrets manager — SSH auth still comes from your existing SSH config, agent, or identity files. No GUI. Surviving a full reboot/logout is also out of scope for v0.1 — see §8. --- ## 2. Data model ### 2.1 Profile A saved definition. Does not imply anything is running. | Field | Type | Notes | |------------------|-----------|-----------------------------------------------------------------------| | `name` | string | Unique key. `[a-z0-9_-]+`, 1-64 chars (matches vmic's naming rule). | | `kind` | enum | `local` \| `remote` \| `dynamic` | | `mapping` | string | Raw `-L/-R/-D` payload, see §5.1 | | `via` | string[] | Ordered hop list; each entry `[user@]host[:port]` (see §3.1) | | `user` | string? | Defaults to current user / `ssh_config` | | `identity` | path? | Identity file override | | `ssh_port` | int | Default `22`; final target only, see §5.1 | | `reconnect` | bool | Default `true` | | `retry_interval` | int (sec) | Default `5`; base reconnect delay (§4.1) | | `backoff_max` | int (sec) | Default `60`; cap on the doubling reconnect delay (§4.1) | | `keepalive` | int (sec) | `ServerAliveInterval`, default `15` | | `created_at` | timestamp | | | `updated_at` | timestamp | | ### 2.2 Instance (runtime state) Exists only while a profile is open. Tracked separately from the profile so `list`/`status` can report live data without touching the saved definition. **The absence of an instance file is what "closed" means** — there is no separate `down` state; see §3 for exactly when the file is created/removed. | Field | Type | Notes | |---------------------|------------|----------------------------------------------------------------| | `name` | string | FK to profile | | `pid` | int | Supervisor process PID, not raw `ssh` PID | | `state` | enum | `up` \| `reconnecting` \| `error` | | `opened_at` | timestamp | Anchor for "session uptime" (§5.5) — set once, at `open` | | `connected_at` | timestamp? | Start of the *current* unbroken connection; resets each reconnect (§5.5) | | `last_error` | string? | Most recent failure message, if any | | `reconnect_count` | int | Since last manual `open` | | `last_reconnect_at` | timestamp? | | ### 2.3 Storage - Profiles: `~/.config/porthole/profiles/.toml` - Runtime state: `~/.local/state/porthole/.json` (written by the supervisor, not hand-edited; absence means the profile is closed) - Lock: `~/.local/state/porthole/.lock` (advisory `flock`, held for the supervisor's entire lifetime — see §3) - Logs: `~/.local/state/porthole/.log`, rotated to a single `.log.1` backup once it exceeds 10 MiB (checked on each reconnect attempt, not per line — these are meant to run for months, unlike vmic's short-lived CLI invocations) --- ## 3. Supervisor architecture `open` has to hand off to a process that keeps running after the invoking shell/terminal exits — the same one-shot-CLI-can't-host-a-daemon problem `vmic` solves by spawning detached `pw-loopback` subprocesses tracked by pid. porthole has no external long-running helper to shell out to (there's no `ssh-loopback` equivalent), so it supervises `ssh` itself via a hidden re-exec of its own binary: 1. `porthole open ` validates the profile, tries to acquire `.lock` (if already held by a live pid: no-op, print status, exit 0 — see §5.2), then spawns *itself* via `std::env::current_exe()` with a hidden subcommand: `porthole __supervise `. 2. The spawned process detaches before doing anything else: `stdin` from `/dev/null`, `stdout`/`stderr` appended to `.log`, and `libc::setsid()` called via `CommandExt::pre_exec` so it leaves the parent's process group/session — it survives the terminal closing and doesn't receive the shell's Ctrl-C/SIGHUP. 3. The foregrounding `open` call blocks briefly (bounded, a few seconds) waiting for the supervisor to write its pid + initial `state` into the instance file, so callers get an accurate exit code for immediate failures (bad auth, port conflict) instead of racing a background process. `-f/--foreground` skips the detach step entirely and runs the supervisor loop inline, attached to the current session. 4. The supervisor's loop: spawn `ssh` with the flags in §3.1, wait on it, classify the exit per §4, sleep/backoff or give up accordingly, and rewrite the instance file after every state change. `close` sends SIGTERM to the *supervisor* pid (not raw `ssh`), which forwards it to its `ssh` child, waits briefly, then exits and removes its lock and instance file. `--force` skips the wait and SIGKILLs both immediately. A supervisor that exits on its own due to a fatal failure (§4.2) leaves the instance file in place with `state: error` rather than deleting it, so the failure stays visible to `status`/`list` until the user acts. ### 3.1 Forced `ssh` flags Every `ssh` invocation porthole spawns gets these, non-configurable, regardless of the user's own `~/.ssh/config`: | Flag | Why | |--------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------| | `-o BatchMode=yes` | A headless supervised process must never block on a password/passphrase/host-key TTY prompt — without this, a first connection to an unknown host or a locked key just hangs forever, indistinguishable from "reconnecting." | | `-o ExitOnForwardFailure=yes` | Makes `ssh` exit non-zero immediately if the requested forward can't be bound, instead of staying up as a plain (forward-less) session that *looks* healthy. | | `-o ConnectTimeout=10` | Bounds how long one connection attempt can hang before porthole's own backoff logic (§4.1) gets a turn. | | `-N` | No remote command — porthole only ever wants the forward, never a shell. | | `-J ` | Only when `--via` is set. The comma-joined hop list is passed to `ssh -J` verbatim — porthole does not re-implement jump-host chaining itself (see §5.1). | `ServerAliveInterval` comes from the profile's `keepalive` field (not hardcoded), so it stays user-tunable. --- ## 4. Reconnect & failure handling ### 4.1 Backoff - Base delay is the profile's `retry_interval` (default 5s). - Each consecutive failed attempt doubles the delay, capped at `backoff_max` (default 60s). - The backoff counter resets to the base delay once a connection has stayed up continuously for 60s — an in-memory supervisor detail, not persisted to the instance file — so one good connection after a flaky patch doesn't leave the *next* reconnect waiting a full capped delay. - If `reconnect` is `false`, there is no retry loop at all: a single failed attempt goes straight to `state: error` and the supervisor exits. ### 4.2 Failure classification `ssh`'s own exit code doesn't reliably distinguish "retry me" from "stop retrying," so porthole classifies by matching `ssh`'s stderr: | Pattern (stderr substring) | Class | Behavior | |-----------------------------------------------------------------|------------|--------------------------------------------------| | `Permission denied` | fatal | `state: error`, stop, supervisor exits | | `Host key verification failed` | fatal | `state: error`, stop, supervisor exits | | `bind: Address already in use` | fatal | `state: error`, stop, supervisor exits | | `Connection refused` / `No route to host` / connect timeout | transient | backoff + retry | | `Could not resolve hostname` | transient | backoff + retry (bounded by `backoff_max`) | | anything else / unrecognized | transient* | backoff + retry, but see escalation below | \* After 10 consecutive unrecognized failures in a row, porthole treats the profile as effectively broken (`state: error`, stop) rather than retrying under an unrecognized failure forever. `last_error` always holds the raw `ssh` message either way, for `status` to show. A profile that lands in `state: error` stays that way — including its instance file — until the user runs `open` again (fresh attempt, fresh backoff) or `close` (clears it). It is deliberately *not* self-healing past a fatal classification. --- ## 5. Commands ### 5.1 `porthole add [flags]` Aliases: `create`, `new` Saves a new profile. Does **not** open it. | Flag | Arg | Required | Default | Description | |--------------------|-------------------------------|-------------------|---------------------------|----------------------------------------| | `-l, --local` | `[bind:]port:host:hostport` | one of `-l/-r/-d` | — | Local forward: your machine → remote | | `-r, --remote` | `[bind:]port:host:hostport` | one of `-l/-r/-d` | — | Remote forward: remote → your machine | | `-d, --dynamic` | `[bind:]port` | one of `-l/-r/-d` | — | Dynamic forward (SOCKS proxy) | | `--via` | `[user@]host[:port][,...]` | no | — | SSH jump-host chain, comma-separated; passed to `ssh -J` verbatim (§3.1) | | `-u, --user` | `user` | no | current user / ssh_config | Default user for the final target and any `--via` hop that doesn't specify its own | | `-i, --identity` | `path` | no | ssh_config default | | | `-p, --port` | `port` | no | `22` | SSH port on the final target only — a `--via` hop needs its own inline `:port` if it isn't 22 | | `--reconnect` | `bool` | no | `true` | Auto-reconnect on drop (§4) | | `--retry-interval` | `seconds` | no | `5` | Base reconnect delay (§4.1) | | `--backoff-max` | `seconds` | no | `60` | Cap on the doubling reconnect delay (§4.1) | | `--keepalive` | `seconds` | no | `15` | `ServerAliveInterval` | Exactly one of `-l`/`-r`/`-d` is required. Providing more than one is an error. **Validation:** - `name` must not already exist (use `edit` to modify); 1-64 chars, `[a-z0-9_-]+`. - `mapping` port syntax validated against the same grammar `ssh` accepts; stored verbatim as whichever `-l/-r/-d` payload was given (without the flag itself) — `kind` records which one it was, so re-deriving the right `-L`/`-R`/`-D` flag at `open` time is a lookup, not a re-parse. - `--via` hosts resolved/checked against `~/.ssh/config` if present, but not required to exist there. **Examples:** ``` porthole add db --local 5432:db.internal:5432 --via jumpbox porthole add admin-ui --local 8080:localhost:8080 --via bastion1,bastion2:2222 --user ops porthole add webhook --remote 9000:localhost:3000 --via public-vps porthole add proxy --dynamic 1080 --via edge-host ``` --- ### 5.2 `porthole open [flags]` Alias: `start` Starts a saved forward as a background-supervised process (§3). | Flag | Description | |--------------------|--------------------------------------------------------------------------------------------------------------------| | `-f, --foreground` | Run attached in current shell instead of detaching. Ctrl-C closes it cleanly (removes the instance file, same as `close`). | | `--once` | Open without auto-reconnect, regardless of profile setting (§4.1). | | `--all` | Ignore ``; open every profile with `reconnect: true` that isn't already running. Per-profile failures are warnings, not a whole-batch failure — this exists specifically as the hook for external autostart mechanisms, see §8. | **Behavior:** - If already open (a live supervisor pid holds `.lock`): no-op, print current status, exit 0. - If the instance file exists but its pid is dead (crash, or the machine rebooted): treated as not-running, proceeds to spawn a fresh supervisor. - If port bind fails (already in use): exit non-zero with the conflicting process info if discoverable (`lsof`-style lookup — best-effort, degrades to a plain "port in use" message if `lsof`/`ss` isn't on `PATH`), don't silently retry. - `open` blocks briefly (bounded, a few seconds) waiting for the detached supervisor to confirm it's alive, so an immediate failure (bad auth, bind conflict) reports a non-zero exit rather than appearing to succeed. Anything that fails *after* that point (a later reconnect) only shows up via `status`/`list`, not `open`'s own exit code. **Examples:** ``` porthole open db porthole open db --foreground porthole open proxy --once porthole open --all ``` --- ### 5.3 `porthole close [flags]` Alias: `stop` Stops a running forward and removes its instance file. Profile definition is untouched. | Flag | Description | |-----------|----------------------------------------------------------------------------------| | `--force` | SIGKILL the supervisor (and its `ssh` child) immediately instead of graceful SIGTERM + wait | `close` on a profile that's already stopped (no live pid) is a no-op, exit 0 — it still clears a stale instance file left over from a crash, same as the crash-recovery path in `open`. **Examples:** ``` porthole close db porthole close db --force ``` --- ### 5.4 `porthole edit [flags]` Updates a saved profile. Accepts the same flags as `add` (all optional — only provided flags are changed). **Decision:** `edit` never restarts a running instance, and there is no `--restart` flag. If `` is currently running, `edit` prints a warning that the change won't take effect until the next `open`/`close` cycle and exits 0 — consistent with vmic's `edit`, which never auto-migrates a live topology without telling the user exactly what to run instead. Keeping this explicit avoids a footgun where editing a profile silently bounces a tunnel someone else might be relying on. **Examples:** ``` porthole edit db --retry-interval 10 porthole edit db --local 5433:db.internal:5432 ``` --- ### 5.5 `porthole status ` Deep-dive health for one forward. | Flag | Description | |----------|-----------------------------------------------------| | `--json` | Machine-readable output (matches `list --json`) | **Output includes:** - Profile summary (kind, mapping, via, user) - Current state (`up` / `reconnecting` / `error`, or `closed` if no instance file exists at all — §2.2) - **Session uptime**: elapsed time since `opened_at` (the original `open` call), regardless of intervening reconnects - **Connection uptime**: elapsed time since `connected_at` (the current unbroken connection) — resets on every reconnect, absent while `reconnecting`/`error` - Reconnect count and timestamp of last reconnect - Last error message, if any - Path to log file **Example:** ``` porthole status db ``` --- ### 5.6 `porthole list` Alias: `ls` All saved profiles with live status. Fast, scannable — no deep diagnostics (use `status` for that). **Columns:** `NAME KIND MAPPING VIA STATE UPTIME` A profile with no instance file shows `STATE: closed` and an empty `UPTIME`. `UPTIME` otherwise shows connection uptime (§5.5). **Flags:** | Flag | Description | |-------------|-------------------------------------------------------------------| | `--running` | Show only currently-open forwards (`STATE` in `up`/`reconnecting`) | | `--json` | Machine-readable output | **Example:** ``` porthole list porthole list --running ``` --- ### 5.7 `porthole remove ` Aliases: `rm`, `delete` Deletes a saved profile. Closes it first if running. | Flag | Description | |------------------|--------------------------------------------------------------------| | `--keep-running` | Delete the profile but leave an active instance running untracked | An instance left running via `--keep-running` is no longer visible to `list`/`status` (its profile is gone), but is still caught by `wipe` (§5.8), which matches by supervisor process signature rather than tracked state — same as vmic's `wipe`. --- ### 5.8 `porthole wipe` Alias: `reset` Closes and deletes **every** forward, including any supervisor/`ssh` processes matching porthole's signature that aren't in the current profile store (e.g. orphaned after a crash). Confirmation prompt unless `--yes` — unlike vmic's `wipe` (no prompt), porthole's tears down active network tunnels rather than just audio routing, so the extra confirmation is a deliberate, not accidental, difference. | Flag | Description | |-------------|----------------------------| | `-y, --yes` | Skip confirmation prompt | --- ### 5.9 `porthole completions ` Generates a shell completion script. `` ∈ `bash`, `zsh`, `fish`. --- ## 6. Global options | Flag | Description | |-----------------|----------------| | `-h, --help` | Print help | | `-V, --version` | Print version | --- ## 7. Exit codes | Code | Meaning | |------|--------------------------------------------------------------------| | `0` | Success | | `1` | Error — see the printed message | | `2` | CLI usage error (bad/missing arguments — clap's own exit code) | Kept deliberately flat, matching vmic: granular per-failure codes (not found vs. already-exists vs. bind conflict, etc.) only pay for themselves once something is actually scripting against them, and nobody's asked for that yet. Every error still gets a specific, greppable message on stderr. --- ## 8. Surviving reboots **Explicitly out of scope for v0.1**, and worth calling out since it's adjacent to the overview's own motivating problem: the supervisor is a plain process, not a system service, so a full reboot or logout kills it along with everything else — reconnect (§4) covers network blips and sleep/wake, not "the machine came back up." The only piece porthole commits to now is `open --all` (§5.2), which exists specifically so an external mechanism can drive it — a systemd `--user` unit, a login item, a cron `@reboot` line. porthole does not register, manage, or template any of those itself; that's a v0.2+ decision (§9) once it's clear which one people actually want. --- ## 9. Open questions for v0.2 - Autostart: if/when to commit to a specific mechanism (systemd user unit template? login item?) now that `open --all` exists as the hook. - Multi-hop `--via`: confirmed as a straight passthrough to `ssh -J` (§3.1/§5.1) for v0.1; revisit only if per-hop supervised status ever becomes a real ask. - Templating (`dbtun`-style): saved "kind" templates (e.g. `--template postgres` implies port 5432) — worth adding as sugar over `add`, or scope creep? - Config export/import for moving profiles between machines.