OpenThinRDP

Replacing Dell ThinOS with OpenThinRDP on Dell thin clients

Dell OptiPlex Thin Clients and Wyse thin clients that run ThinOS are 64-bit x86 PCs with UEFI. OpenThinRDP runs
on them like on any other PC: the production fleet OpenThinRDP comes from is Dell OptiPlex 3000 Thin Clients that ran
ThinOS before, and they connect every day to a Windows 11 VDI through two RD Connection Brokers.

This guide is for networks built on Windows Remote Desktop (RDS session hosts, a VDI collection, or Windows PCs).
If your users need Citrix or Omnissa Horizon, keep ThinOS: OpenThinRDP does RDP only.

1. Write down what ThinOS connects to

From the ThinOS configuration, or from Wyse Management Suite, write down:

ThinOS OpenThinRDP setting
the RD Connection Broker or session host BROKER (and BROKER_FALLBACK for a second broker)
the collection (VDI pool or RemoteApp/desktop collection) LOAD_BALANCE_INFO, as loadbalanceinfo in the .rdp file, e.g. tsv://VMResource.1.VDI
the domain DOMAIN, its full DNS name for Kerberos (e.g. example.local)
an RD Gateway, for devices outside the office RDP_GATEWAY
USB devices redirected whole (signature keys, special devices) USB_REDIRECT (VID:PID list)

Everything else (network, time, power schedule, logo) is set the same way: all the settings.

2. Firmware settings

Open the firmware setup (F2 at power on on Dell devices). On devices that came with ThinOS it is often protected
by an administrator password: Dell documents a default one for its thin clients, and ThinOS or Wyse Management Suite
may have set another.

Once OpenThinRDP runs, these settings can also be read and changed from Linux through dell-wmi-sysman, without the
setup screen (hardware).

3. Try it live, nothing installed

  1. Write the ISO to a USB stick (Rufus in DD mode,
    balenaEtcher or dd).
  2. Start the thin client from the stick (F12). The live system starts by itself after 10 seconds and never writes
    to the internal disk    : ThinOS is still there when you remove the stick.
  3. In the settings dialog set the broker, the collection and the domain, save, and sign in as a user.

Check what matters to you before installing: the monitors, the USB devices your users plug in, the webcam and
headset in Teams, smart cards, sound. The diagnostics (ℹ on the sign-in screen) show the network, the brokers and the
time.

4. Install

Restart from the stick and choose Install. The installer shows the disk it is going to erase and asks; answer
Yes and it takes about three minutes. It installs on the internal disk (eMMC or SSD), never on a USB disk.

Installing erases ThinOS. Going back needs Dell's recovery image for that model: make sure you can get it before
you install, if you may want to go back. For many devices, the Unattended install entry of the boot menu skips the
question.

5. Many devices: the management folder

Instead of Wyse Management Suite, OpenThinRDP uses a shared folder (SMB) and a Windows tool, with no server:

  1. Create the folder, e.g. \\fileserver\thinclients, with an account the devices use to write their status
    (management).
  2. Put the common settings in config\common.conf (broker, collection, domain...), and the settings of a single
    device in config\<hostname>.conf.
  3. Set MGMT_SHARE on each device, or build your own image with it (building).
  4. Run the manager: the state of every device, settings for all or one, the screen of any device,
    updates that go to a few pilot devices first, and going back to the version before when something breaks.

6. What changes for the users

Questions: FAQ. Compared with ThinOS and the others: alternatives.