CyberHunter
Local dataset, no network
// Other services

Port 104: ACR-NEMA Digital Imag. & Comm. 300

Port 104 is assigned by IANA to acr-nema (ACR-NEMA Digital Imag. & Comm. 300).

104

How acr-nema works

Other services
client:104acr-nemaresponse client:104acr-nemaresponse

The client sends a request to port 104 and the acr-nema 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 104 dangerous?

We have no specific security note for port 104. 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 104

ServicePortTransportDescriptionReferenceUpdated
acr-nema 104 TCP, UDP ACR-NEMA Digital Imag. & Comm. 300 - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 104, and is it reachable?

Linux

sudo ss -ltnup 'sport = :104'      # process listening on 104
sudo lsof -nP -i :104

macOS

sudo lsof -nP -i :104

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 104 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 104
netstat -ano | findstr :104

From another machine

nmap -p 104 -sV <host>
sudo nmap -sU -p 104 <host>
nc -zv <host> 104

Block it in the firewall

sudo ufw deny 104/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 104" -Direction Inbound -LocalPort 104 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 104 used for?

Port 104 is assigned by IANA to acr-nema (ACR-NEMA Digital Imag. & Comm. 300).

Is port 104 TCP or UDP?

Port 104 is registered for TCP and UDP.

Is it safe to open port 104?

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 104 is open?

On Linux run "ss -ltnup 'sport = :104'", on macOS "lsof -nP -i :104", and on Windows "netstat -ano | findstr :104" to see the local process. From another machine, "nmap -p 104 <host>" shows whether it is reachable.

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