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// DevOps, cloud & containers

Port 4841: QUOSA Virtual Library Service

Port 4841 is assigned by IANA to quosa (QUOSA Virtual Library Service).

4841

How quosa works

DevOps, cloud & containers
adminhostquosa adminhostquosa

Commands sent to port 4841 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 4841 dangerous?

We have no specific security note for port 4841. 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 4841

ServicePortTransportDescriptionReferenceUpdated
quosa 4841 TCP, UDP QUOSA Virtual Library Service - 2006-09

// source: IANA service name and port number registry

03 Check it

Which program uses port 4841, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4841'      # process listening on 4841
sudo lsof -nP -i :4841

macOS

sudo lsof -nP -i :4841

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4841 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4841
netstat -ano | findstr :4841

From another machine

nmap -p 4841 -sV <host>
sudo nmap -sU -p 4841 <host>
nc -zv <host> 4841

Block it in the firewall

sudo ufw deny 4841/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4841" -Direction Inbound -LocalPort 4841 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4841 used for?

Port 4841 is assigned by IANA to quosa (QUOSA Virtual Library Service).

Is port 4841 TCP or UDP?

Port 4841 is registered for TCP and UDP.

Is it safe to open port 4841?

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 4841 is open?

On Linux run "ss -ltnup 'sport = :4841'", on macOS "lsof -nP -i :4841", and on Windows "netstat -ano | findstr :4841" to see the local process. From another machine, "nmap -p 4841 <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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