# Windows host.id not unique **URL:** \ **Category:** Elastic Agent\ **Created:** [January 28, 2025, 12:47pm UTC](https://discuss.elastic.co/t/windows-host-id-not-unique/373767 "2025-01-28T12:47:51Z")\ **Posts on this page:** 1\ **Showing post:** 3
**Author:** ![agg-mb](https://avatars.discourse-cdn.com/v4/letter/a/7c8e57/32.png) [@agg-mb](https://discuss.elastic.co/u/agg-mb)\ **Post date:** [January 5, 2026, 3:15pm UTC](https://discuss.elastic.co/t/windows-host-id-not-unique/373767/3 "2026-01-05T15:15:01Z")
Hello, we are facing a similar issue, see also: > [@Installation of Elastic Agents on Non-Persistent VDI Machines](https://discuss.elastic.co/t/installation-of-elastic-agents-on-non-persistent-vdi-machines/377504): > > Hello, We have a use case where we'd like to monitor hundreds of Citrix VDI desktops. Those are machines that are regularly rebooted and are built based on an image that's prebuilt... We have 1 image that is pushed to VDI machines in 2 different network environments, i.e Elastic agents also talk to 2 different Fleet Servers. I saw 2 similar previous question and issue that were raised around this same topic, but never got answers to? [Issue with Elastic Agent ID duplication · Issue #37743 ·…](https://github.com/elastic/beats/issues/37743) The duplicate `host.id` might be caused by e.g. non-persistent VDIs or when you duplicate machines from a “golden image”. See also my post about a way to alter the `host.id`: > > > As a user, I would like to have a uniquely created \`host.id\` even when using VM …(VDI, virtual desktop infrastructure) > > \*\*The problem:\*\* > > The \`host.id\` isn't unique enough, we are using \`elastic/go-sysinfo\` to generate the \`host.id\` from hardware information but if you have two VM from the same images it's possible that the \`host.id\` is the same. > > !\[image (4)\](https://user-images.githubusercontent.com/640/97618104-ff3f8680-19f4-11eb-9e8e-7153f8bda809.png) This can easily be done via registry in Windows and (although not tested by me: for Linux & MacOS it could be possible to alter these values): > The `add_host_metadata` processor adds a `host.id` field to every Beat event by default. The value is retrieved in go-sysinfo: > > - Linux: Reads `/etc/machine-id`, `/var/lib/dbus/machine-id`, and `/var/db/dbus/machine-id`. ([machineid.go](https://github.com/elastic/go-sysinfo/blob/master/providers/linux/machineid.go)) > > - macOS: `IOPlatformUUID` via the `gethostuuid` API call. (`machineid_darwin_amd64.go`) > > - Windows: Registry key `HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography\MachineGuid` ([machineid\_windows.go](https://github.com/elastic/go-sysinfo/blob/master/providers/windows/machineid_windows.go)) See also: > > > \*Original comment by @ph:\* > > As Fleet API, I want to make sure the machine talkin…g to me is the same machine that was enrolled. > > To do that we want to generate a fingerprint of the machine and use that fingerprint as a machine-id, > I think we could use theses source to create the ID, we could also add the mac address to it. > > \- OS X uses IOPlatformUUID > \- BSD uses /etc/hostid (smbios.system.uuid fallback) > \- Linux uses /var/lib/dbus/machine-id > \- Windows LINK REDACTED > > We should not expose that key directly to the api, we should cryptographically hash the key. I hope this helps. By altering the `MachineGuid` I could find a way to circumvent the duplicate `host.id` values. A solution could be a script that checks its `hostname` against a table of generated custom UUIDs and setting the corresponding `MachineGuid` to the matching value in the list. This way even for non-persistent VDIs there could be a way to have “persistent”, “unique” `host.id`s. --- _[View the full topic](https://discuss.elastic.co/t/windows-host-id-not-unique/373767)._