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// Other services

Port 2921: CESD Contents Delivery Management

Port 2921 is assigned by IANA to cesdcdman (CESD Contents Delivery Management).

2921

How cesdcdman works

Other services
client:2921cesdcdmanresponse client:2921cesdcdmanresponse

The client sends a request to port 2921 and the cesdcdman 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 2921 dangerous?

We have no specific security note for port 2921. 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 2921

ServicePortTransportDescriptionReferenceUpdated
cesdcdman 2921 TCP, UDP CESD Contents Delivery Management - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2921, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2921'      # process listening on 2921
sudo lsof -nP -i :2921

macOS

sudo lsof -nP -i :2921

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2921 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2921
netstat -ano | findstr :2921

From another machine

nmap -p 2921 -sV <host>
sudo nmap -sU -p 2921 <host>
nc -zv <host> 2921

Block it in the firewall

sudo ufw deny 2921/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2921" -Direction Inbound -LocalPort 2921 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2921 used for?

Port 2921 is assigned by IANA to cesdcdman (CESD Contents Delivery Management).

Is port 2921 TCP or UDP?

Port 2921 is registered for TCP and UDP.

Is it safe to open port 2921?

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 2921 is open?

On Linux run "ss -ltnup 'sport = :2921'", on macOS "lsof -nP -i :2921", and on Windows "netstat -ano | findstr :2921" to see the local process. From another machine, "nmap -p 2921 <host>" shows whether it is reachable.

05 Related
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