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// IoT & industrial (ICS)

Port 17756: ZigBee IP Transport Secure Service

Port 17756 is assigned by IANA to zigbee-ips (ZigBee IP Transport Secure Service).

17756

How zigbee-ips works

IoT & industrial (ICS)
controllerPLCzigbee-ipsno authentication controllerPLCzigbee-ipsno authentication

A controller sends commands to an industrial device on port 17756, which acts on the physical process.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
IoT & industrial (ICS)
01 Security

Is port 17756 dangerous?

We have no specific security note for port 17756. Its risk depends on the program actually listening on it. General advice for iot & industrial (ics) services:

  • Industrial and IoT protocols often have no authentication: never expose them to the Internet.
  • Segment OT networks from IT and use protocol-aware firewalls.
  • Monitor with an ICS-aware intrusion detection system.
02 Registry

IANA registry entries for port 17756

ServicePortTransportDescriptionReferenceUpdated
zigbee-ips 17756 TCP, UDP ZigBee IP Transport Secure Service - 2006-05

// source: IANA service name and port number registry

03 Check it

Which program uses port 17756, and is it reachable?

Linux

sudo ss -ltnup 'sport = :17756'      # process listening on 17756
sudo lsof -nP -i :17756

macOS

sudo lsof -nP -i :17756

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 17756 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 17756
netstat -ano | findstr :17756

From another machine

nmap -p 17756 -sV <host>
sudo nmap -sU -p 17756 <host>
nc -zv <host> 17756

Block it in the firewall

sudo ufw deny 17756/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 17756" -Direction Inbound -LocalPort 17756 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 17756 used for?

Port 17756 is assigned by IANA to zigbee-ips (ZigBee IP Transport Secure Service).

Is port 17756 TCP or UDP?

Port 17756 is registered for TCP and UDP.

Is it safe to open port 17756?

It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Industrial and IoT protocols often have no authentication: never expose them to the Internet.

How do I check if port 17756 is open?

On Linux run "ss -ltnup 'sport = :17756'", on macOS "lsof -nP -i :17756", and on Windows "netstat -ano | findstr :17756" to see the local process. From another machine, "nmap -p 17756 <host>" shows whether it is reachable.

05 Related
:1883 MQTT tcp · udp · high risk :8883 MQTT over TLS tcp · udp · moderate risk :502 Modbus TCP tcp · udp · critical risk :102 Siemens S7 (ISO-TSAP) tcp · udp · critical risk :47808 BACnet udp · tcp · critical risk :20000 DNP3 tcp · udp · sctp · critical risk :44818 EtherNet/IP tcp · udp · critical risk :802 Modbus Application Protocol Secure tcp · udp

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