CyberHunter
Local dataset, no network
// Other services

Port 524: NCP

Port 524 is assigned by IANA to ncp (NCP).

524

How ncp works

Other services
client:524ncpresponse client:524ncpresponse

The client sends a request to port 524 and the ncp 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 524 dangerous?

We have no specific security note for port 524. 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 524

ServicePortTransportDescriptionReferenceUpdated
ncp 524 TCP, UDP NCP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 524, and is it reachable?

Linux

sudo ss -ltnup 'sport = :524'      # process listening on 524
sudo lsof -nP -i :524

macOS

sudo lsof -nP -i :524

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 524 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 524
netstat -ano | findstr :524

From another machine

nmap -p 524 -sV <host>
sudo nmap -sU -p 524 <host>
nc -zv <host> 524

Block it in the firewall

sudo ufw deny 524/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 524" -Direction Inbound -LocalPort 524 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 524 used for?

Port 524 is assigned by IANA to ncp (NCP).

Is port 524 TCP or UDP?

Port 524 is registered for TCP and UDP.

Is it safe to open port 524?

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 524 is open?

On Linux run "ss -ltnup 'sport = :524'", on macOS "lsof -nP -i :524", and on Windows "netstat -ano | findstr :524" to see the local process. From another machine, "nmap -p 524 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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