CyberHunter
Local dataset, no network
// Other services

Port 999: Applix ac

Port 999 is assigned by IANA to applix (Applix ac), garcon (), puprouter ().

999

How applix works

Other services
client:999applixresponse client:999applixresponse

The client sends a request to port 999 and the applix service answers.

Transport
UDP · TCP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned3 registered services
Range
Well-known (0-1023)
Category
Other services
01 Security

Is port 999 dangerous?

We have no specific security note for port 999. 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 999

ServicePortTransportDescriptionReferenceUpdated
applix 999 UDP Applix ac - -
garcon 999 TCP - -
puprouter 999 TCP, UDP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 999, and is it reachable?

Linux

sudo ss -ltnup 'sport = :999'      # process listening on 999
sudo lsof -nP -i :999

macOS

sudo lsof -nP -i :999

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 999 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 999
netstat -ano | findstr :999

From another machine

nmap -p 999 -sV <host>
sudo nmap -sU -p 999 <host>
nc -zv <host> 999

Block it in the firewall

sudo ufw deny 999/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 999" -Direction Inbound -LocalPort 999 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 999 used for?

Port 999 is assigned by IANA to applix (Applix ac), garcon (), puprouter ().

Is port 999 TCP or UDP?

Port 999 is registered for UDP and TCP.

Is it safe to open port 999?

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 999 is open?

On Linux run "ss -ltnup 'sport = :999'", on macOS "lsof -nP -i :999", and on Windows "netstat -ano | findstr :999" to see the local process. From another machine, "nmap -p 999 <host>" shows whether it is reachable.

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