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Local dataset, no network
// DevOps, cloud & containers

Port 3343: MS Cluster Net

Port 3343 is assigned by IANA to ms-cluster-net (MS Cluster Net).

3343

How ms-cluster-net works

DevOps, cloud & containers
adminhostms-cluster-net adminhostms-cluster-net

Commands sent to port 3343 create and control containers or cluster resources on the host.

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
DevOps, cloud & containers
01 Security

Is port 3343 dangerous?

We have no specific security note for port 3343. Its risk depends on the program actually listening on it. General advice for devops, cloud & containers services:

  • Container and orchestration APIs give full control of hosts: require mutual TLS and RBAC.
  • Never expose them to the Internet.
  • Rotate tokens and certificates and audit who has access.
02 Registry

IANA registry entries for port 3343

ServicePortTransportDescriptionReferenceUpdated
ms-cluster-net 3343 TCP, UDP MS Cluster Net - 2009-02-12

// source: IANA service name and port number registry

03 Check it

Which program uses port 3343, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3343'      # process listening on 3343
sudo lsof -nP -i :3343

macOS

sudo lsof -nP -i :3343

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3343 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3343
netstat -ano | findstr :3343

From another machine

nmap -p 3343 -sV <host>
sudo nmap -sU -p 3343 <host>
nc -zv <host> 3343

Block it in the firewall

sudo ufw deny 3343/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3343" -Direction Inbound -LocalPort 3343 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3343 used for?

Port 3343 is assigned by IANA to ms-cluster-net (MS Cluster Net).

Is port 3343 TCP or UDP?

Port 3343 is registered for TCP and UDP.

Is it safe to open port 3343?

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. Container and orchestration APIs give full control of hosts: require mutual TLS and RBAC.

How do I check if port 3343 is open?

On Linux run "ss -ltnup 'sport = :3343'", on macOS "lsof -nP -i :3343", and on Windows "netstat -ano | findstr :3343" to see the local process. From another machine, "nmap -p 3343 <host>" shows whether it is reachable.

05 Related
:2375 Docker API (HTTP) tcp · critical risk :2376 Docker API (TLS) tcp · high risk :6443 Kubernetes API tcp · udp · high risk :10250 Kubelet API tcp · critical risk :2379 etcd tcp · critical risk :8500 Consul tcp · udp · high risk :4505 SaltStack tcp · critical risk :9000 PHP-FPM / SonarQube / Portainer tcp · udp · high risk

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