# WHATPORT(1091)

## NAME

port 1091 — FOUNDATION Fieldbus HSE — System Management — System management for FOUNDATION Fieldbus HSE: device addressing, tags, and schedule synchronisation.

Protocol: TCP  
IANA registry

## DESCRIPTION

System Management is the FOUNDATION Fieldbus service that assigns device addresses and tags, locates devices by tag, and keeps function-block execution schedules synchronised across a segment. The Fieldbus Foundation registered it on 1091 as the third of the HSE ports. It appears on linking devices and gateways from process-automation vendors, and its presence is a strong indicator of an industrial network segment.

## EXPOSURE

**Do not expose.** This service can address and re-tag field devices. It must stay inside the plant control network, firewalled from IT and unreachable from the internet.

## CHECK

```sh
nmap -sV -Pn -p 1091 TARGET
```

## SEE ALSO

- iana — [IANA port registry — 1091 (ff-sm)](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=1091) (iana.org)
- source — [ITI/ICS-Security-Tools — ICS protocol port list (FOUNDATION Fieldbus HSE, 1089-1091)](https://github.com/ITI/ICS-Security-Tools/blob/master/protocols/PORTS.md) (github.com)

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HTML: <https://whatport.net/1091/> · JSON: <https://whatport.net/1091.json> · full dataset: <https://whatport.net/ports.json>