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// Other services

Port 3751: CommLinx GPRS Cube

Port 3751 is assigned by IANA to gprs-cube (CommLinx GPRS Cube).

3751

How gprs-cube works

Other services
client:3751gprs-cuberesponse client:3751gprs-cuberesponse

The client sends a request to port 3751 and the gprs-cube 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 3751 dangerous?

We have no specific security note for port 3751. 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 3751

ServicePortTransportDescriptionReferenceUpdated
gprs-cube 3751 TCP, UDP CommLinx GPRS Cube - 2003-04

// source: IANA service name and port number registry

03 Check it

Which program uses port 3751, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3751'      # process listening on 3751
sudo lsof -nP -i :3751

macOS

sudo lsof -nP -i :3751

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3751 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3751
netstat -ano | findstr :3751

From another machine

nmap -p 3751 -sV <host>
sudo nmap -sU -p 3751 <host>
nc -zv <host> 3751

Block it in the firewall

sudo ufw deny 3751/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3751" -Direction Inbound -LocalPort 3751 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3751 used for?

Port 3751 is assigned by IANA to gprs-cube (CommLinx GPRS Cube).

Is port 3751 TCP or UDP?

Port 3751 is registered for TCP and UDP.

Is it safe to open port 3751?

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 3751 is open?

On Linux run "ss -ltnup 'sport = :3751'", on macOS "lsof -nP -i :3751", and on Windows "netstat -ano | findstr :3751" to see the local process. From another machine, "nmap -p 3751 <host>" shows whether it is reachable.

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