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// Network services

Port 17221: IEEE 1722.1 AVB Discovery, Enumeration, Connection management, and Control

Port 17221 is assigned by IANA to avdecc (IEEE 1722.1 AVB Discovery, Enumeration, Connection management, and Control).

17221

How avdecc works

Network services
client:17221avdeccresponse client:17221avdeccresponse

The client sends a request to port 17221 and the avdecc service answers.

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
Network services
01 Security

Is port 17221 dangerous?

We have no specific security note for port 17221. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 17221

ServicePortTransportDescriptionReferenceUpdated
avdecc 17221 TCP, UDP IEEE 1722.1 AVB Discovery, Enumeration, Connection management, and Control - 2011-11-01

// source: IANA service name and port number registry

03 Check it

Which program uses port 17221, and is it reachable?

Linux

sudo ss -ltnup 'sport = :17221'      # process listening on 17221
sudo lsof -nP -i :17221

macOS

sudo lsof -nP -i :17221

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 17221 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 17221
netstat -ano | findstr :17221

From another machine

nmap -p 17221 -sV <host>
sudo nmap -sU -p 17221 <host>
nc -zv <host> 17221

Block it in the firewall

sudo ufw deny 17221/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 17221" -Direction Inbound -LocalPort 17221 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 17221 used for?

Port 17221 is assigned by IANA to avdecc (IEEE 1722.1 AVB Discovery, Enumeration, Connection management, and Control).

Is port 17221 TCP or UDP?

Port 17221 is registered for TCP and UDP.

Is it safe to open port 17221?

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. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 17221 is open?

On Linux run "ss -ltnup 'sport = :17221'", on macOS "lsof -nP -i :17221", and on Windows "netstat -ano | findstr :17221" to see the local process. From another machine, "nmap -p 17221 <host>" shows whether it is reachable.

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