CyberHunter
Local dataset, no network
// Other services

Port 1591: ncpm-pm

Port 1591 is assigned by IANA to ncpm-pm (ncpm-pm).

1591

How ncpm-pm works

Other services
client:1591ncpm-pmresponse client:1591ncpm-pmresponse

The client sends a request to port 1591 and the ncpm-pm 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 1591 dangerous?

We have no specific security note for port 1591. 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 1591

ServicePortTransportDescriptionReferenceUpdated
ncpm-pm 1591 TCP, UDP ncpm-pm - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 1591, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1591'      # process listening on 1591
sudo lsof -nP -i :1591

macOS

sudo lsof -nP -i :1591

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1591 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1591
netstat -ano | findstr :1591

From another machine

nmap -p 1591 -sV <host>
sudo nmap -sU -p 1591 <host>
nc -zv <host> 1591

Block it in the firewall

sudo ufw deny 1591/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1591" -Direction Inbound -LocalPort 1591 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1591 used for?

Port 1591 is assigned by IANA to ncpm-pm (ncpm-pm).

Is port 1591 TCP or UDP?

Port 1591 is registered for TCP and UDP.

Is it safe to open port 1591?

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 1591 is open?

On Linux run "ss -ltnup 'sport = :1591'", on macOS "lsof -nP -i :1591", and on Windows "netstat -ano | findstr :1591" to see the local process. From another machine, "nmap -p 1591 <host>" shows whether it is reachable.

05 Related
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