CyberHunter
Local dataset, no network
// Other services

Port 4099: DPCP

Port 4099 is assigned by IANA to dpcp (DPCP).

4099

How dpcp works

Other services
client:4099dpcpresponse client:4099dpcpresponse

The client sends a request to port 4099 and the dpcp 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
Other services
01 Security

Is port 4099 dangerous?

We have no specific security note for port 4099. 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 4099

ServicePortTransportDescriptionReferenceUpdated
dpcp 4099 TCP, UDP DPCP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 4099, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4099'      # process listening on 4099
sudo lsof -nP -i :4099

macOS

sudo lsof -nP -i :4099

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4099 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4099
netstat -ano | findstr :4099

From another machine

nmap -p 4099 -sV <host>
sudo nmap -sU -p 4099 <host>
nc -zv <host> 4099

Block it in the firewall

sudo ufw deny 4099/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4099" -Direction Inbound -LocalPort 4099 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4099 used for?

Port 4099 is assigned by IANA to dpcp (DPCP).

Is port 4099 TCP or UDP?

Port 4099 is registered for TCP and UDP.

Is it safe to open port 4099?

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 4099 is open?

On Linux run "ss -ltnup 'sport = :4099'", on macOS "lsof -nP -i :4099", and on Windows "netstat -ano | findstr :4099" to see the local process. From another machine, "nmap -p 4099 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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