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cookingwithsimon merged 2 commits into from
Oct 16, 2026
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Phase 3: static IP finder, Reach it, subnet scan and device discovery #7

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Phase 3: static IP finder, Reach it, subnet scan and device discovery
claude Oct 16, 2026
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Merge branch 'main' of https://github.com/cookingwithsimon/prodhcpser…
claude Oct 16, 2026
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17 changes: 13 additions & 4 deletions README.md
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Expand Up @@ -6,7 +6,7 @@ Plug your laptop into a DSP, camera, switcher, display or control processor, pre

![ProDHCPServer main window in dark mode](docs/images/main-window-dark.png)

> **Status:** Phases 1 (the core DHCP loop) and 2 (ping graphs, session log export, profiles) are done and passed their hardware tests in October 2026. Phase 3 (discovery) is next. See [Roadmap](#roadmap).
> **Status:** Phases 1 (the core DHCP loop) and 2 (ping graphs, session log export, profiles) are done and passed their hardware tests in October 2026. Phase 3 (finding devices) is being built. See [Roadmap](#roadmap).

## Why

Expand Down Expand Up @@ -43,6 +43,14 @@ Most AV kit ships set to DHCP, and on a bench or a fresh site there's usually no

![The Profiles panel with the Default preset and links to the manufacturers' documentation](docs/images/profiles-panel-dark.png)

**Phase 3 (in progress)**

- **Static IP finder.** While the server runs, the **Found on the network** list shows every device heard on the cable that didn't take an address from the server, including ones with a static IP on another subnet. A device shows up as soon as it sends anything (a broadcast, an mDNS or UPnP announcement, a vendor beacon), and with Npcap installed, as soon as it powers up (its ARP check).
- **Reach it.** One click adds a temporary address on the device's subnet to your adapter, so you can open its WebUI without stopping the DHCP server. The address is removed on Stop, on exit and after a crash, like every other change. If Wi-Fi is on that subnet, the app offers to turn it off until Stop.
- **Scan for static IPs.** For quiet devices: ARPs every address on your subnet, the brand presets' factory subnets (192.168.254.x, 192.168.0.x, 192.168.1.x) and any subnet a device was seen on, using a temporary address on each that's removed straight after.
- **Discovery protocols:** mDNS/DNS-SD (including Sennheiser SSC and Dante Domain Manager), SSDP/UPnP (with the device's own name and model), PJLink (projectors and displays), Art-Net (lighting nodes), AES67 stream announcements (SAP), AMX Device Discovery beacons, AMX NetLinx, Q-SYS and Shure discovery. Every query is read-only. Sources are in [docs/vendor-discovery.md](docs/vendor-discovery.md).
- **Switch port.** With [Npcap](https://npcap.com) installed, shows which managed switch and port you're plugged into, and its VLAN, from LLDP or CDP. Everything else works without Npcap.

**Default profile:** server IP `192.168.100.1/24`, addresses `192.168.100.100` to `192.168.100.199`, 60-minute leases. Make your own profile under **Profiles** (the gear button) to change any of these.

## Download and run
Expand All @@ -67,7 +75,8 @@ Most AV kit ships set to DHCP, and on a bench or a fresh site there's usually no
|---|---|
| Red banner: another DHCP server is on the link | You're plugged into a network that already hands out addresses (office, venue, home router). Unplug from it, or only use **Serve anyway** on a network you own. |
| Step 2 red, "No link" | No cable, a dead port, or the device is off. Steps 2 to 4 recover by themselves when the link comes up. |
| Step 5 amber, no DHCP requests after 30 seconds | The device probably has a static IP or DHCP turned off. |
| Step 5 amber, no DHCP requests after 30 seconds | The device probably has a static IP or DHCP turned off. Look under **Found on the network**, or press **Scan for static IPs**, then **Reach it**. |
| A device isn't found | Some devices stay silent until spoken to. Press **Scan for static IPs**. If it's on a subnet the scan doesn't cover, power-cycle it with Npcap installed: its ARP check at power-up shows its address. |
| The device gets an offer but never accepts it | Some embedded network stacks ignore their own broadcast flag. Tick **Always broadcast replies** in your profile and try again. |
| Step 1 amber, mentions Wi-Fi or VPN | Another adapter is on the same subnet. Use **Turn it off until Stop**, or use a profile with a different server IP. |
| Step 2 says the cable shows connected but nothing has been received | The USB network adapter has stopped receiving. Unplug it from the laptop and plug it back in. If step 1 mentions an old Realtek driver, install the newer one: Windows Settings > Windows Update > Advanced options > Optional updates > Driver updates, tick the Realtek one only. |
Expand All @@ -90,7 +99,7 @@ Each phase ends with a hardware test pass on real AV equipment before the next o

- **Phase 1: core loop** (done, hardware-tested October 2026).
- **Phase 2: visibility** (done, hardware-tested October 2026). Continuous ping with a latency graph per device, a full session log you can filter and export (TXT/CSV), and saved profiles for subnet, pool, lease time and DHCP options (router, DNS, NTP, option 43/66/150 and custom options).
- **Phase 3: discovery.** Find devices that already have a static IP, move your adapter onto their subnet in one click, and discover devices via mDNS (including Dante), SSDP/UPnP and LLDP/CDP.
- **Phase 3: discovery** (in progress). Find devices that already have a static IP, reach their subnet in one click, and discover devices via mDNS, SSDP/UPnP, vendor protocols and LLDP/CDP.

## Files it writes

Expand Down Expand Up @@ -122,7 +131,7 @@ dotnet publish src/ProDHCPServer.App -c Release -r win-x64 -o publish
| `src/ProDHCPServer.Windows` | Windows specifics: adapter reading and changes, the UDP 67 socket, ARP entries, firewall rule, other-server probe, ping and port checks. |
| `src/ProDHCPServer.App` | The WPF app: UI, elevation prompt, crash handling. |
| `tests/` | Core unit tests (run anywhere) and Windows integration tests (run on the Windows CI runner and never change adapter settings). |
| `docs/` | Hardware test checklists for each phase, and the screenshots used in this README (taken by the CI smoke test). |
| `docs/` | Hardware test checklists for each phase, the sources for the discovery protocols (`vendor-discovery.md`), and the screenshots used in this README (taken by the CI smoke test). |
| `tools/` | CI smoke test (launches the app and takes screenshots) and the manufacturer list updater (`python3 tools/update-oui.py`). |

**CI.** Every push and pull request runs the **Build and test** workflow on Windows: build, Core and Windows tests, publish the exe, and a smoke test that screenshots the app in light and dark mode. The exe and screenshots are uploaded as run artifacts.
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# Phase 3 hardware test

About 30 minutes. You need:

- The unmanaged laptop.
- Two AV devices on a small unmanaged switch (the NAV E and NAV SD are ideal).
- One device you can set to a **static IP on a different subnet**. For example, set the NAV SD to 192.168.1.50 /24 in its web page, or use anything still on a factory static address such as an Extron switcher at 192.168.254.254.
- A managed switch with LLDP or CDP turned on, if you have one, for section 5.

Download `ProDHCPServer.exe` from the latest successful **Build and test** run on the Phase 3 pull request (Actions tab → run → Artifacts → `ProDHCPServer-win-x64`). Click **More info → Run anyway** on the SmartScreen warning.

Tick each box. If something fails, use **Export log…** and send me the file.

## 1. Found on the network

- [ ] Press **Start** with both devices on the switch, one of them on its static IP. Under the device list there's a **Found on the network** section saying it's listening.
- [ ] Within a minute, the static device appears there with its IP, an amber light and "Static IP on 192.168.1.x, which this laptop isn't on yet". If it doesn't, power-cycle it.
- [ ] The DHCP device is **not** listed there (it's in **All devices** above).
- [ ] After 30 s with no DHCP request from the static device, step 5 names it: "No DHCP requests…, but 192.168.1.50 (…) is on the cable with a static IP."
- [ ] The session log has a "Found 192.168.1.50 … It has a static IP on another subnet" line.

## 2. Reach it

- [ ] Press **Reach it** on the static device. Within a few seconds its light turns green, the line says "This laptop can reach it", and **Open WebUI** appears.
- [ ] The log says "Added 192.168.1.249/24 to "Ethernet" so this laptop can reach 192.168.1.50. It's removed when you press Stop."
- [ ] **Open WebUI** opens the device's web page.
- [ ] The DHCP device still works the whole time (its ping graph keeps going).
- [ ] Press **Stop**, then check the adapter in Windows (`ipconfig`): 192.168.1.249 is gone and the adapter is back to how it was.

## 3. Scan for static IPs

- [ ] Unplug the static device, Start, and plug it back in only after the server is running. If it doesn't show up by itself, press **Scan for static IPs**.
- [ ] The line under the button counts through the subnets ("Scanning 192.168.1.x (2 of 5)…") and ends with "Scan finished: N devices answered." It takes a minute or two.
- [ ] The static device is listed with its MAC and manufacturer, found by "subnet scan".
- [ ] While it scans, `ipconfig` shows one extra temporary address at a time; when it finishes, none are left.
- [ ] Press **Scan for static IPs** again and press **Stop** while it's still scanning: the adapter goes back to its original settings with no leftover addresses.

## 4. Discovery protocols

Tick what applies to the gear you have; skip the rest.

- [ ] A device that advertises itself (Dante, Q-SYS, Sennheiser, Shure, a ClickShare or most network players) shows its own name, found by mDNS, UPnP, Q-SYS or Shure.
- [ ] A projector or display with PJLink turned on shows up, found by PJLink, within about 30 s.
- [ ] Hover over a found device: the tooltip lists what it said (services, model, firmware).

## 5. Switch port (needs Npcap)

Only if you're happy to install [Npcap](https://npcap.com/#download) on the test laptop (free, a normal installer).

- [ ] Without Npcap: the section says "Install Npcap to see which switch port you're plugged into…", and **Get Npcap** opens the download page.
- [ ] With Npcap, through a managed switch with LLDP or CDP on: within about 30 s a line says "Plugged into <switch> port <port>, VLAN <n>". The log has the same line.
- [ ] With Npcap, power-cycle the static device: it appears within seconds of booting, found by ARP.

## 6. Phases 1 and 2 still work

- [ ] Quick repeat: one device straight on the cable, Start, lease, ping graph and WebUI green, **Open WebUI**, **Export log…**, Stop, adapter back to its original settings.
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