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// Other services

Port 8901: JMB-CDS 2

Port 8901 is assigned by IANA to jmb-cds2 (JMB-CDS 2).

8901

How jmb-cds2 works

Other services
client:8901jmb-cds2response client:8901jmb-cds2response

The client sends a request to port 8901 and the jmb-cds2 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 8901 dangerous?

We have no specific security note for port 8901. 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 8901

ServicePortTransportDescriptionReferenceUpdated
jmb-cds2 8901 TCP, UDP JMB-CDS 2 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 8901, and is it reachable?

Linux

sudo ss -ltnup 'sport = :8901'      # process listening on 8901
sudo lsof -nP -i :8901

macOS

sudo lsof -nP -i :8901

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 8901 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 8901
netstat -ano | findstr :8901

From another machine

nmap -p 8901 -sV <host>
sudo nmap -sU -p 8901 <host>
nc -zv <host> 8901

Block it in the firewall

sudo ufw deny 8901/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 8901" -Direction Inbound -LocalPort 8901 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 8901 used for?

Port 8901 is assigned by IANA to jmb-cds2 (JMB-CDS 2).

Is port 8901 TCP or UDP?

Port 8901 is registered for TCP and UDP.

Is it safe to open port 8901?

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 8901 is open?

On Linux run "ss -ltnup 'sport = :8901'", on macOS "lsof -nP -i :8901", and on Windows "netstat -ano | findstr :8901" to see the local process. From another machine, "nmap -p 8901 <host>" shows whether it is reachable.

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