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// Other services

Port 21848: NetSpeak Corp. Automatic Call Distribution

Port 21848 is assigned by IANA to netspeak-acd (NetSpeak Corp. Automatic Call Distribution).

21848

How netspeak-acd works

Other services
client:21848netspeak-acdresponse client:21848netspeak-acdresponse

The client sends a request to port 21848 and the netspeak-acd 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 21848 dangerous?

We have no specific security note for port 21848. 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 21848

ServicePortTransportDescriptionReferenceUpdated
netspeak-acd 21848 TCP, UDP NetSpeak Corp. Automatic Call Distribution - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 21848, and is it reachable?

Linux

sudo ss -ltnup 'sport = :21848'      # process listening on 21848
sudo lsof -nP -i :21848

macOS

sudo lsof -nP -i :21848

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 21848 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 21848
netstat -ano | findstr :21848

From another machine

nmap -p 21848 -sV <host>
sudo nmap -sU -p 21848 <host>
nc -zv <host> 21848

Block it in the firewall

sudo ufw deny 21848/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 21848" -Direction Inbound -LocalPort 21848 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 21848 used for?

Port 21848 is assigned by IANA to netspeak-acd (NetSpeak Corp. Automatic Call Distribution).

Is port 21848 TCP or UDP?

Port 21848 is registered for TCP and UDP.

Is it safe to open port 21848?

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 21848 is open?

On Linux run "ss -ltnup 'sport = :21848'", on macOS "lsof -nP -i :21848", and on Windows "netstat -ano | findstr :21848" to see the local process. From another machine, "nmap -p 21848 <host>" shows whether it is reachable.

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