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// Other services

Port 3889: D and V Tester Control Port

Port 3889 is assigned by IANA to dandv-tester (D and V Tester Control Port).

3889

How dandv-tester works

Other services
client:3889dandv-testerresponse client:3889dandv-testerresponse

The client sends a request to port 3889 and the dandv-tester 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 3889 dangerous?

We have no specific security note for port 3889. 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 3889

ServicePortTransportDescriptionReferenceUpdated
dandv-tester 3889 TCP, UDP D and V Tester Control Port - 2003-10

// source: IANA service name and port number registry

03 Check it

Which program uses port 3889, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3889'      # process listening on 3889
sudo lsof -nP -i :3889

macOS

sudo lsof -nP -i :3889

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3889 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3889
netstat -ano | findstr :3889

From another machine

nmap -p 3889 -sV <host>
sudo nmap -sU -p 3889 <host>
nc -zv <host> 3889

Block it in the firewall

sudo ufw deny 3889/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3889" -Direction Inbound -LocalPort 3889 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3889 used for?

Port 3889 is assigned by IANA to dandv-tester (D and V Tester Control Port).

Is port 3889 TCP or UDP?

Port 3889 is registered for TCP and UDP.

Is it safe to open port 3889?

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 3889 is open?

On Linux run "ss -ltnup 'sport = :3889'", on macOS "lsof -nP -i :3889", and on Windows "netstat -ano | findstr :3889" to see the local process. From another machine, "nmap -p 3889 <host>" shows whether it is reachable.

05 Related
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