DSH One Gateway

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Share DSH Web with the people you choose — not your whole network.

A DeepSeek Harness (DSH) plugin that puts a private, zero-trust gateway in front of DSH Web. Callers authenticate through Tailscale Serve, Cloudflare Access, or — on Headscale — a generated gateway credential in front of private TCP Serve. One private allowlist decides who gets in. There is no user-chosen password to manage.

The gateway and DSH stay on loopback. Tailscale Serve, Cloudflare Tunnel with Cloudflare Access, or Headscale via Tailscale TCP Serve is only the private ingress. Joining that private network is never an authorization decision. Every request must resolve one unambiguous, allowlisted principal before anything is forwarded to DSH. That is self-hosted access control for a zero trust homelab: reachability is not permission.

Allowlisted browser ─ HTTPS ─> provider ingress (Tailscale Serve, Cloudflare Access,
                                      │           or Headscale TCP Serve)
                                      └─ loopback gateway ─> local DSH
                                         127.0.0.1:3088   127.0.0.1:3080

What you get: an exact principal allowlist in front of DSH, a loopback-only HTTP/WebSocket proxy, and a single onboarding command that previews a plan and refuses public or anonymous defaults. Installing the plugin does nothing until you run setup.

The full command is dsh-one-gateway; a shorter dsh-gateway alias is installed too, for typing convenience.

How this is different

Other DSH gateways may bind off loopback, patch DSH internals so a gate stays exhaustive after upgrades, or run a reverse proxy in front of DSH. Those designs can cover /api and WebSockets too; the difference is not who covers more of the surface. This plugin is a different contract: DSH itself never leaves loopback.

1. Private network membership is never authorization. Binding 0.0.0.0 or treating RFC1918 as an allow is out of scope. The listener stays on loopback. Being on the same Wi-Fi, tailnet, or mesh does not get you in.
2. Fail-closed DSH origin. DSH stays on loopback; the gateway is the only listener in front of it. A DSH upgrade cannot silently add a route that becomes reachable off-host — there is no gate route table to keep exhaustive, because DSH was never reachable off-host to begin with. A missed route in a full-coverage gate is a silent bypass; a missed route in this bridge just breaks that one proxied path. It does not expose DSH.
3. No DSH-core or client-library patches. Some gates stay exhaustive by patching DSH HTTP and upgrade entry points, then re-applying those patches after every upgrade — because an upstream change can silently undo them. This gateway is an external process. DSH's own code is never modified.
4. For Tailscale Serve and Cloudflare Access, identity comes from the provider — not a login page, password, or shared token. Password forms, shared tokens, and session-cookie doors are a large auth surface and a common source of bugs. Those two shipped modes use Serve's injected Tailscale-User-Login, or a locally verified Cloudflare Access JWT. We check an allowlist. We do not ask you to invent a password. gateway-credential is a smaller, purpose-built login for transports with no native identity: a generated per-principal credential (not a user-chosen password), verifier-only storage, a bounded HttpOnly/Secure/SameSite=Strict session, individual revocation, and rate limiting without permanent lockout. Compared with a typical user-chosen or shared password, that is stronger on guessability, storage disclosure, and revocation; it is not "passwordless" and not a claim of superiority over every password or passkey. Headscale TCP Serve is the shipped transport that uses this mode. For any transport-only provider with no native identity, the contract is a product-owned bridge from the private overlay to the unchanged loopback gateway, authenticated with gateway-credential — never a fabricated identity header.
5. One plugin, one onboarding command, one allowlist. Instead of a different bespoke setup per provider, Tailscale Serve, Cloudflare Tunnel with Access, and Headscale TCP Serve share one loopback gateway. A new provider is another adapter, not another product.

What this plugin does not do

• Make DSH itself multi-tenant, or reduce the privileges of an allowlisted user (every allowlisted principal is a full DSH administrator).
• Treat device, node, or mesh membership as human identity.
• Expose a configurable generic reverse proxy or an arbitrary trusted-header name.
• Support public anonymous tunnels, Funnel, or Cloudflare quick tunnels.
• Manage provider-wide ACLs, DNS zones, or account policies.
• Auto-remove persistent provider routes on uninstall.
• Accept user-chosen passwords.
• Run more than one ingress provider in one gateway instance.
• Protect you from a malicious same-host administrator or any process that can already read DSH memory/configuration or connect directly to DSH loopback.

Supported providers

Provider	Auth mode	What identity it proves	What setup does
Tailscale Serve	trusted-header — Serve injects a login header	Exact Tailscale-User-Login injected by Serve after it overwrites a caller-supplied value. Not “anyone on the tailnet”.	Can create one missing private Serve route for you (routeManagement: ensure), or only check that the route already exists (verify-only).
Cloudflare Tunnel with Access	signed-jwt — locally validates an Access identity token	A locally validated Access identity JWT (Cf-Access-Jwt-Assertion, RS256, issuer, audience, email, non-empty sub). Not a convenience email header, not a service token, not “the hostname is private”.	You configure the Access application yourself and point it only at the gateway. Setup verifies local JWT settings (routeManagement: verify-only); it cannot independently prove Access stays attached to the tunnel.
Headscale via Tailscale TCP Serve	gateway-credential — possession of a gateway secret	Possession of a distinct high-entropy gateway credential issued per operator. TCP Serve supplies private reachability only; it has no HTTP identity header and does not prove who you are.	Can create one missing private TCP Serve forward to 127.0.0.1:3088 (ensure), or only check that it exists (verify-only). You supply the TLS certificate and key. Setup on Tailscale.com steers you to identity-aware Tailscale Serve instead.
EasyTier	gateway-credential — possession of a gateway secret	Possession of a distinct high-entropy gateway credential. EasyTier is transport only.	Not shipped.

Private reachability is not authorization. A tailnet member, a Cloudflare hostname that is internet-routable, or a mesh peer can reach an endpoint and still receive 403 unless the gateway allowlist matches.

Cloudflare nuance: Access-gated applications are often reachable from the Internet. Packets can arrive unauthenticated. The supported product shape is an identity-gated application plus mandatory local JWT validation, never an anonymous public tunnel. Local token validation is solid. The gateway cannot machine-prove that Access remains attached to the tunnel without broad account credentials; setup says so, and it still refuses a missing or invalid JWT.

Quick start

You need a working local DSH Web profile and Node.js 20+ (normally supplied by DSH).

1. Install the plugin. This neither starts a listener nor changes provider state. Nothing is exposed until you run setup.

   dsh plugin --profile web add -w /path/to/dsh-one-gateway
   

2. Run guided setup and confirm the displayed plan.

   In a terminal, omit --provider to choose from a menu. Operators on Tailscale.com are steered to identity-aware Tailscale Serve; Headscale TCP Serve is listed when the live node is on Headscale. Detection of a local executable is a hint and, when exactly one provider is found, a default — not a configuration check. Pass --provider to skip the menu. Non-interactive setup still auto-selects when exactly one provider executable is detected, and otherwise requires --provider.

   Tailscale Serve:

   dsh plugin --profile web exec dsh-gateway -- setup --provider tailscale-serve
   

   Cloudflare Access (you configure Access yourself; the gateway only verifies the token locally). You must already have an Access application forwarding only to 127.0.0.1:3088:

   dsh plugin --profile web exec dsh-gateway -- setup --provider cloudflare-access \
     --external-origin 'https://dsh.example.invalid' \
     --team-origin 'https://team.example.invalid' \
     --application-audience 'replace-with-access-application-audience' \
     --trusted-principal 'email:operator@example.invalid'
   

   In a TTY, omitted Cloudflare values are collected interactively in this order: existing Access origin, team origin, application audience, trusted email. Unattended --yes still requires all four flags. Setup never creates a tunnel, DNS record, or Access application.

   Headscale TCP Serve (private reachability plus a generated gateway credential; you supply the certificate). Setup on Tailscale.com will not offer this as an equal menu choice:

   dsh plugin --profile web exec dsh-gateway -- setup --provider headscale-tcp-serve \
     --tls-cert /path/to/dsh-one-gateway/cert.pem \
     --tls-key /path/to/dsh-one-gateway/key.pem \
     --credential-store /path/to/dsh-one-gateway/credentials.json \
     --trusted-principal operator-1
   

   TCP Serve does not terminate HTTPS and does not prove identity. The gateway terminates TLS on 127.0.0.1:3088 with that operator-supplied certificate. Clients must trust the certificate; this pass does not generate a private CA. After confirmation, setup issues one credential, prints the raw secret once, and never writes it to the profile. --print issues nothing.

   Confirmation writes an enabled profile entry. Setup never guesses, kills, or restarts your supervisor. Restart the DSH Web process you already own.

3. Open the configured HTTPS origin as an allowlisted principal. Port 3088 itself remains unreachable from the LAN and from the provider network.

Use --print to preview without writing. In a TTY, --print may still prompt for a provider and missing values, but it never writes a profile, provider resource, or credential. Non-interactive --yes requires every security-sensitive value to be supplied explicitly. --yes skips only the final write confirmation; it does not invent a provider or Cloudflare values.

What each auth mode proves

These auth.mode values are the literal YAML keys. Each one is paired with a fixed provider; you cannot mix them.

• trusted-header (Tailscale only). Serve injected exactly one Tailscale-User-Login and the value is on the allowlist as login:<exact-login>. The header name is fixed in code. You cannot configure a generic header.
• signed-jwt (Cloudflare Access only). The request carried exactly one Cf-Access-Jwt-Assertion that verifies against the team JWKS, with the configured issuer and application audience, required exp/iat/nbf, identity type, scalar email, and non-empty sub. The allowlist uses email:<exact-email>. The CF_Authorization cookie is never trusted.
• gateway-credential (Headscale TCP Serve). Possession of a distinct ≥256-bit credential issued per operator (CLI- generated, not a user-chosen password), submitted in a POST body from the JSON API or a same-origin login form — never a URL query parameter — and exchanged for a short-lived __Host- session cookie (HttpOnly, Secure, SameSite=Strict). The gateway stores only a verifier hash; sessions are individually revocable and attempts are rate-limited without permanent lockout. TCP Serve does not contribute identity: being able to reach the node is not authorization. Tailscale Serve and Cloudflare Access cannot select this mode.

After setup

dsh-gateway doctor
dsh-gateway credential issue --store /path/to/dsh-one-gateway/credentials.json --name operator-1
dsh-gateway credential list --store /path/to/dsh-one-gateway/credentials.json
dsh-gateway credential revoke --store /path/to/dsh-one-gateway/credentials.json --name operator-1

Disable by setting enabled: false on the generated profile entry and restarting DSH. Uninstall does not remove Tailscale Serve routes, Cloudflare tunnels, Access applications, or credential files. Remove those yourself.

Threat model and local-host trust boundary

The gateway defends against spoofed identity headers, public-mode provider configuration, Host/Origin/request-target smuggling, provider tokens leaking into DSH, stale JWT keys, and config typos that would broaden exposure. See SECURITY.md.

It does not defend against a process on the same host that can connect to 127.0.0.1:3080 or 127.0.0.1:3088, read the DSH profile, or act as a local root. Loopback TCP cannot prove which local executable opened it. Same-host compromise is out of scope.

TLS, keys, and credentials

• Profile YAML never contains private keys, JWTs, or issued credential secrets.
• Cloudflare signing keys are fetched from the team origin JWKS path with bounded HTTPS; they are not written to the profile.
• Headscale TCP Serve requires an operator-supplied certificate and private key (absolute paths, restrictive key permissions, matching pair, unexpired, SAN covering externalOrigin). The gateway does not generate a CA or self-signed certificate. Clients must enroll trust for that certificate.
• Gateway credentials (when used) store only a verifier at an operator-supplied absolute path with restrictive permissions. The raw secret is shown once.
• Backup the credential store as you would any other secret file; revocation is per principal. Sessions are in-memory and drop when the gateway process restarts.

Troubleshooting

Do not disable auth, Origin checks, TLS, or provider verification to “just get it working”.

Symptom	What to check
Gateway never becomes ready	dsh-gateway doctor; Tailscale Serve conflict/Funnel; TCP Serve conflict/Funnel; TLS cert/key; Cloudflare JWKS fetch; missing allowlist
403 for an expected user	Exact, case-sensitive principal (login: / email:); duplicate identity headers; missing Origin on POST/API/WebSocket
Setup refuses to write	Existing dsh-gateway or legacy dsh-tailscale-gateway entry; non-list YAML; missing --yes values
Cloudflare still 403 with Access	Identity token missing/expired; wrong audience; service token (no email); Access not attached (probe may report unprotected)

Not supported yet

These may map onto the same contracts later. “It is a VPN” is not enough.

• EasyTier / ZeroTier / WireGuard-only — no application-level identity (the mapping is gateway-credential). All three stay out today for one shared reason: this codebase cannot yet prove a listener is bound exclusively to the private overlay interface, not merely that it reports the right local address. Linux and macOS have SO_BINDTODEVICE / IP_BOUND_IF for that; Node's net.Server.listen() exposes neither. That is a specific engineering gap, not a claim that these transports cannot work. There is no shipped adapter for them, and no committed schedule.
• Headscale HTTPS Serve — still blocked. Headscale does not provide Tailscale's identity-aware HTTPS Serve. The shipped Headscale path is raw TCP Serve plus gateway-credential and an operator-supplied certificate, not a fabricated identity header.
• NetBird — claimed identity headers are unsupported until a cited overwrite profile and integration test exist.
• Twingate / Pangolin — no frozen JWT/header validation profile.
• Generic reverse proxy / arbitrary trusted-header — too easy to configure with a spoofable header.
• Raw LAN, SSH tunnel, public tunnel — outside the private-ingress contract.

The older dsh-tailscale-gateway package remains a Tailscale-only reference product. The two gateway processes cannot bind the same fixed gateway port at once. Setup detects a legacy profile entry and refuses to append another.

Configuration

Only the exact fields shown below are accepted. Unknown keys are errors. There are no listenHost, listenPort, upstream, headerName, jwksUrl, allowAnonymous, trustPrivateNetwork, public, or funnel keys.

Tailscale — trusted-header means Serve injects the login; routeManagement: ensure means setup will create one missing private Serve route:

enabled: true
externalOrigin: 'https://gateway.example-tailnet.ts.net:8443'
provider:
  type: tailscale-serve
  routeManagement: ensure
auth:
  mode: trusted-header
  trustedPrincipals:
    - 'login:operator@example.invalid'

Headscale TCP Serve — gateway-credential means possession of a generated secret; TCP Serve is private reachability only. tls is required:

enabled: true
externalOrigin: 'https://gateway.example.invalid:8443'
provider:
  type: headscale-tcp-serve
  routeManagement: ensure
tls:
  certPath: '/path/to/dsh-one-gateway/cert.pem'
  keyPath: '/path/to/dsh-one-gateway/key.pem'
auth:
  mode: gateway-credential
  trustedPrincipals:
    - 'credential:operator-1'
  credentialStorePath: '/path/to/dsh-one-gateway/credentials.json'

Cloudflare — signed-jwt means the gateway locally validates the Access identity JWT; routeManagement: verify-only means you attach Access yourself:

enabled: true
externalOrigin: 'https://dsh.example.invalid'
provider:
  type: cloudflare-access
  routeManagement: verify-only
  teamOrigin: 'https://team.example.invalid'
  applicationAudience: 'replace-with-access-application-audience'
auth:
  mode: signed-jwt
  trustedPrincipals:
    - 'email:operator@example.invalid'

License

MIT. See LICENSE.