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// Other services

Port 16003: Automation and Control by REGULACE.ORG

Port 16003 is assigned by IANA to alfin (Automation and Control by REGULACE.ORG).

16003

How alfin works

Other services
client:16003alfinresponse client:16003alfinresponse

The client sends a request to port 16003 and the alfin service answers.

Transport
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
Other services
01 Security

Is port 16003 dangerous?

We have no specific security note for port 16003. Its risk depends on the program actually listening on it. General advice for other services services:

  • Close the port if nothing on the host needs it.
  • Identify the process that listens on it (commands below) before opening it in a firewall.
  • Expose a service only to the networks that use it.
02 Registry

IANA registry entries for port 16003

ServicePortTransportDescriptionReferenceUpdated
alfin 16003 UDP Automation and Control by REGULACE.ORG - 2010-10-06
-16003-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 16003, and is it reachable?

Linux

sudo ss -ltnup 'sport = :16003'      # process listening on 16003
sudo lsof -nP -i :16003

macOS

sudo lsof -nP -i :16003

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 16003 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 16003
netstat -ano | findstr :16003

From another machine

nmap -p 16003 -sV <host>
sudo nmap -sU -p 16003 <host>
nc -zv <host> 16003

Block it in the firewall

sudo ufw deny 16003/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 16003" -Direction Inbound -LocalPort 16003 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 16003 used for?

Port 16003 is assigned by IANA to alfin (Automation and Control by REGULACE.ORG).

Is port 16003 TCP or UDP?

Port 16003 is registered for UDP.

Is it safe to open port 16003?

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. Close the port if nothing on the host needs it.

How do I check if port 16003 is open?

On Linux run "ss -ltnup 'sport = :16003'", on macOS "lsof -nP -i :16003", and on Windows "netstat -ano | findstr :16003" to see the local process. From another machine, "nmap -p 16003 <host>" shows whether it is reachable.

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