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Local dataset, no network
// Other services

Port 423: IBM Operations Planning and Control Start

Port 423 is assigned by IANA to opc-job-start (IBM Operations Planning and Control Start).

423

How opc-job-start works

Other services
client:423opc-job-startresponse client:423opc-job-startresponse

The client sends a request to port 423 and the opc-job-start 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 423 dangerous?

We have no specific security note for port 423. 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 423

ServicePortTransportDescriptionReferenceUpdated
opc-job-start 423 TCP, UDP IBM Operations Planning and Control Start - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 423, and is it reachable?

Linux

sudo ss -ltnup 'sport = :423'      # process listening on 423
sudo lsof -nP -i :423

macOS

sudo lsof -nP -i :423

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 423 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 423
netstat -ano | findstr :423

From another machine

nmap -p 423 -sV <host>
sudo nmap -sU -p 423 <host>
nc -zv <host> 423

Block it in the firewall

sudo ufw deny 423/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 423" -Direction Inbound -LocalPort 423 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 423 used for?

Port 423 is assigned by IANA to opc-job-start (IBM Operations Planning and Control Start).

Is port 423 TCP or UDP?

Port 423 is registered for TCP and UDP.

Is it safe to open port 423?

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 423 is open?

On Linux run "ss -ltnup 'sport = :423'", on macOS "lsof -nP -i :423", and on Windows "netstat -ano | findstr :423" to see the local process. From another machine, "nmap -p 423 <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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