Port 2873PubSub Realtime Telemetry Protocol

Port 2873 is assigned to Altertech’s PubSub Realtime Telemetry Protocol (PSRT); its real-world deployment is not established.

inIoT

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 1/10
lookups: 0

also known as psrt

Technical Details

what runs on :2873

PubSub Realtime Telemetry Protocol is registered on port :2873 over tcp and udp to Altertech, assigned November 2021. We don't have a technical write-up for it beyond the IANA registry entry.

In nmap's internet-wide scan data this port is never observed open, so if it's open on your network it's more likely a custom or misconfigured service than the registered one.

find what's listening on :2873

this machine

# linux
sudo ss -tulpn 'sport = :2873'

# macos / bsd
sudo lsof -nP -i :2873

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :2873

another host

nmap -sV -p T:2873 <host>
sudo nmap -sU -sV -p U:2873 <host>

run it? the handshake, the implementations you meet in the wild and the flags that matter come from the engineers who do.

add technical details

Security Information

exposure of :2873

risk score

1/ 10safe

routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.

iot averages 3.4 across 149 ports — this one sits 2.4 below.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

tcp · udp

udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite

security overview

no security notes recorded for :2873 yet

known exploits, hardening advice, what a compromise looks like — suggest an edit if you know its exposure.

Record

iana registry entry

port: :2873
service: PubSub Realtime Telemetry Protocol
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: IoT
usage: IANA assigns TCP and UDP port 2873 to the PubSub Realtime Telemetry Protocol and lists Altertech as the registrant. No independently established implementation or common deployment is known.
lookups: 0rank 993
added: 2026-09-25
updated: 2026-09-25
references: IANA service name registry — port 2873

Something wrong?

This record is maintained by the engineers who use port 2873. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-09-25.

01edit any field on a page of its own
02a model checks it for accuracy and spam
03clean and confident goes live immediately

edit this record →back to the registry

Related Ports

all 149 in iot →

the 8 most looked-up other ports in iot — 149 ports carry that label.

port	service	proto	category	risk	views
:6543	Jetnet	UDP	Network Services	caution	65.3k
:3233	WhiskerControl Protocol	TCPUDP	Network Services	caution	61.9k
:9600	Omron FINS Communication	UDP	Network Services	caution	33.2k
:4840	OPC UA TCP	TCPUDP	Network Services	caution	26.6k
:5678	Mikrotik MNDP	UDP	Network Services	caution	24.7k
:4843	OPC UA over TLS/SSL	TCPUDPtls	Security	caution	24.6k
:5001	Slingbox	TCP	Streaming	caution	22.4k
:15000	Hypack Data Acquisition	TCP	Network Services	caution	21.4k

risk mix of the 8 listed

caution100%

1 of 8 encrypted

Port :2873PubSub Realtime Telemetry Protocol

Technical Details

Security Information

Related Ports

Port 2873PubSub Realtime Telemetry Protocol