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// DevOps, cloud & containers

Port 3509: Virtual Token SSL Port

Port 3509 is assigned by IANA to vt-ssl (Virtual Token SSL Port).

3509

How vt-ssl works

DevOps, cloud & containers
adminhostvt-ssl adminhostvt-ssl

Commands sent to port 3509 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 3509 dangerous?

We have no specific security note for port 3509. 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 3509

ServicePortTransportDescriptionReferenceUpdated
vt-ssl 3509 TCP, UDP Virtual Token SSL Port - 2002-05

// source: IANA service name and port number registry

03 Check it

Which program uses port 3509, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3509'      # process listening on 3509
sudo lsof -nP -i :3509

macOS

sudo lsof -nP -i :3509

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3509 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3509
netstat -ano | findstr :3509

From another machine

nmap -p 3509 -sV <host>
sudo nmap -sU -p 3509 <host>
nc -zv <host> 3509

Block it in the firewall

sudo ufw deny 3509/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3509" -Direction Inbound -LocalPort 3509 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3509 used for?

Port 3509 is assigned by IANA to vt-ssl (Virtual Token SSL Port).

Is port 3509 TCP or UDP?

Port 3509 is registered for TCP and UDP.

Is it safe to open port 3509?

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 3509 is open?

On Linux run "ss -ltnup 'sport = :3509'", on macOS "lsof -nP -i :3509", and on Windows "netstat -ano | findstr :3509" to see the local process. From another machine, "nmap -p 3509 <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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