dsh-lan

Lan gateway + machine switcher for the DeepSeek Harness Web GUI.

Each machine running this plugin exposes its loopback DSH (127.0.0.1:3080) to the LAN through a small gateway on port 4080 (HTTP + WebSocket reverse proxy that rewrites Host/Origin so the browser-trust fence lets remote /api requests through — no --trusted-host needed), plus a UDP discovery beacon on port 4081 so every machine learns about the others. A sidebar button opens a switcher that embeds any discovered machine's GUI via an iframe.

Why 4080 and not 3080

The DSH web server is deliberately bound to 127.0.0.1:3080 only. Its web stack never exposes the LAN interface, and the CLI hard-rejects --host 0.0.0.0 ("intentionally not supported yet for safety: it would expose remote code execution to the network"). Reason: the DSH GUI drives an agent that can run arbitrary commands on the host, so exposing the server directly is an RCE risk the authors intentionally close.

So http://<ip>:3080/ is never reachable from another machine — that's not a fault, it's by design. The gateway on 4080 is the actual LAN front door: it binds 0.0.0.0:4080 as a separate process (it does not touch the DSH webserver, so the loopback-only whitelist does not apply), then reverse-proxies into 127.0.0.1:3080. Use http://<lan-ip>:4080/ from other machines.

Install

# from the plugin checkout (this directory)
dsh plugin --profile web add ./dsh-lan
# restart dsh web to activate
dsh web

Installing runs pnpm add in the web profile; because package.json declares dsh.bundle.patch, the reconcile step also appends dsh-lan to dsh.profile.bundles. Restart is required for the composition (and the browser client roster) to pick it up.

Use

1. Open the DSH GUI on any machine (localhost or via a gateway URL).
2. Click 远程 at the sidebar foot → the remote switcher opens, listing the local machine plus any discovered/added LAN machines.
3. Click 连接管理 → a dialog where you can add, edit, and delete manual connections. Each connection stores a computer name, an IP address, and a port (default 4080). Connections you save here appear in the switcher dropdown.
4. Pick one from the dropdown → that machine's full GUI is embedded; switch back to 本机 anytime. A "新标签打开当前" link opens the remote GUI in its own tab.

Direct access also works: http://<lan-ip>:4080/.

What the remote device actually sees

Accessing http://<host>:4080/ drives that host's single DSH process (the gateway just proxies into it). The remote device is not a second, independent DSH — it is another screen into the same backend. So it shows the host's exact workspaces and sessions, and anything you open from the remote lands in the same places as from the host. That is automatically synchronized: there is no separate state to merge.

If instead you run separate DSH instances on multiple machines, each has its own workspaces/sessions; the switcher lets you jump between machines, but DSH has no cross-instance session sync — pick one machine's gateway if you need the data to be identical.

Config

Stored in $DSH_HOME/.dsh-lan/config.json (created on first run) and editable in the switcher UI:

{
  "port": 4080,
  "discoveryPort": 4081,
  "token": "",
  "manualPeers": [
    { "name": "studio", "ip": "192.168.1.50", "port": 4080 }
  ]
}

• token — optional shared secret. When set, every gateway request needs ?token=<token> (or a cookie set on first navigation). Configure the SAME token on every machine so the selector can open peers. Empty = open access.
• manualPeers — machines to include even if UDP discovery is blocked (different VLAN, firewall, etc.).

Firewall

Allow inbound for the gateway and discovery on every machine (admin shell):

netsh advfirewall firewall add rule name="dsh-lan-gateway" dir=in action=allow protocol=TCP localport=4080 profile=private
netsh advfirewall firewall add rule name="dsh-lan-discover" dir=in action=allow protocol=UDP localport=4081 profile=private

Troubleshooting / verify

Is the gateway actually up? (run on the host that runs DSH)

Get-NetTCPConnection -LocalPort 4080,3080 -State Listen | Select-Object LocalAddress,LocalPort,OwningProcess
# expect: 3080 -> 127.0.0.1 (DSH, loopback),  4080 -> 0.0.0.0 (gateway up)

• 4080 absent → the plugin is not active: make sure dsh plugin add ran, dsh web was restarted, and the profile's dsh.profile.bundles lists dsh-lan.
• 4080 bound but a LAN peer can't reach it → firewall rule missing (the gateway binding does not open the OS firewall).
• Test from another machine, not from localhost — a localhost 200 only proves the bind, not LAN reachability.

crypto.randomUUID is not a function when adding a workspace (or any operation) over http://<ip>:4080/ — that web API only exists in a secure context (HTTPS or localhost). Over plain-HTTP LAN access the browser exposes crypto.getRandomValues but not crypto.randomUUID. The gateway injects a small polyfill (built on getRandomValues) into every HTML page it proxies, so workspace creation and RPC ids work over HTTP. If you still hit it, hard-refresh the remote browser (Ctrl+Shift+R) to pick up the polyfilled page.

Layout

lib/index.js    host plugin (Node ESM): spawns the gateway child, seeds config.json
lib/client.js   browser module (ModuleLoader CJS): footer button + switcher overlay
cordis.patch.yml  profile patch: inserts the host row `dsh-lan`

Security

The gateway exposes the machine's DSH to the LAN — the model there can run commands and read/write arbitrary files, so the gateway is effectively full machine control. Use it only on a trusted LAN and set a shared token. Privileged DSH methods (settings.update, credentials.*, host.openPath, llm.discoverModels, …) are not auth-gated by the gateway; only the shared token stands between a peer and your machine.

If stronger protection is wanted (the gateway is still an RCE surface), either add HTTP Basic Auth in front of the gateway or use the account/session login from dsh-plugin-remote.

Differences from dsh-plugin-remote

dsh-plugin-remote adds scrypt login + session cookies + WebRTC desktop projection. This plugin keeps no login (optional shared token) and focuses on multi-machine discovery + one-click switching. Add a login layer if the LAN is not trusted.