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// Other services

Port 1841: netopia-vo3

Port 1841 is assigned by IANA to netopia-vo3 (netopia-vo3).

1841

How netopia-vo3 works

Other services
client:1841netopia-vo3response client:1841netopia-vo3response

The client sends a request to port 1841 and the netopia-vo3 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 1841 dangerous?

We have no specific security note for port 1841. 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 1841

ServicePortTransportDescriptionReferenceUpdated
netopia-vo3 1841 TCP, UDP netopia-vo3 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1841, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1841'      # process listening on 1841
sudo lsof -nP -i :1841

macOS

sudo lsof -nP -i :1841

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1841 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1841
netstat -ano | findstr :1841

From another machine

nmap -p 1841 -sV <host>
sudo nmap -sU -p 1841 <host>
nc -zv <host> 1841

Block it in the firewall

sudo ufw deny 1841/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1841" -Direction Inbound -LocalPort 1841 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1841 used for?

Port 1841 is assigned by IANA to netopia-vo3 (netopia-vo3).

Is port 1841 TCP or UDP?

Port 1841 is registered for TCP and UDP.

Is it safe to open port 1841?

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 1841 is open?

On Linux run "ss -ltnup 'sport = :1841'", on macOS "lsof -nP -i :1841", and on Windows "netstat -ano | findstr :1841" to see the local process. From another machine, "nmap -p 1841 <host>" shows whether it is reachable.

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