CyberHunter
// Other services

Port 3969: Landmark Messages

Port 3969 is assigned by IANA to landmarks (Landmark Messages).

3969

How landmarks works

Other services
client:3969landmarksresponse client:3969landmarksresponse

The client sends a request to port 3969 and the landmarks 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)
01 Security

Is port 3969 dangerous?

We have no specific security note for port 3969. 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 3969

ServicePortTransportDescriptionReferenceUpdated
landmarks 3969 TCP, UDP Landmark Messages - 2005-08

// source: IANA service name and port number registry

03 Check it

Which program uses port 3969, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3969'      # process listening on 3969
sudo lsof -nP -i :3969

macOS

sudo lsof -nP -i :3969

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3969 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3969
netstat -ano | findstr :3969

From another machine

nmap -p 3969 -sV <host>
sudo nmap -sU -p 3969 <host>
nc -zv <host> 3969

Block it in the firewall

sudo ufw deny 3969/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3969" -Direction Inbound -LocalPort 3969 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3969 used for?

Port 3969 is assigned by IANA to landmarks (Landmark Messages).

Is port 3969 TCP or UDP?

Port 3969 is registered for TCP and UDP.

Is it safe to open port 3969?

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 3969 is open?

On Linux run "ss -ltnup 'sport = :3969'", on macOS "lsof -nP -i :3969", and on Windows "netstat -ano | findstr :3969" to see the local process. From another machine, "nmap -p 3969 <host>" shows whether it is reachable.

05 Related