CyberHunter
Local dataset, no network
// Other services

Port 4751: Simple Policy Control Protocol

Port 4751 is assigned by IANA to spocp (Simple Policy Control Protocol).

4751

How spocp works

Other services
client:4751spocpresponse client:4751spocpresponse

The client sends a request to port 4751 and the spocp 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 4751 dangerous?

We have no specific security note for port 4751. 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 4751

ServicePortTransportDescriptionReferenceUpdated
spocp 4751 TCP, UDP Simple Policy Control Protocol - 2005-08

// source: IANA service name and port number registry

03 Check it

Which program uses port 4751, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4751'      # process listening on 4751
sudo lsof -nP -i :4751

macOS

sudo lsof -nP -i :4751

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4751 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4751
netstat -ano | findstr :4751

From another machine

nmap -p 4751 -sV <host>
sudo nmap -sU -p 4751 <host>
nc -zv <host> 4751

Block it in the firewall

sudo ufw deny 4751/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4751" -Direction Inbound -LocalPort 4751 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4751 used for?

Port 4751 is assigned by IANA to spocp (Simple Policy Control Protocol).

Is port 4751 TCP or UDP?

Port 4751 is registered for TCP and UDP.

Is it safe to open port 4751?

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 4751 is open?

On Linux run "ss -ltnup 'sport = :4751'", on macOS "lsof -nP -i :4751", and on Windows "netstat -ano | findstr :4751" to see the local process. From another machine, "nmap -p 4751 <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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