CyberHunter
Local dataset, no network
// Other services

Port 2391: 3COM Net Management

Port 2391 is assigned by IANA to 3com-net-mgmt (3COM Net Management).

2391

How 3com-net-mgmt works

Other services
client:23913com-net-mgmtresponse client:23913com-net-mgmtresponse

The client sends a request to port 2391 and the 3com-net-mgmt 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 2391 dangerous?

We have no specific security note for port 2391. 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 2391

ServicePortTransportDescriptionReferenceUpdated
3com-net-mgmt 2391 TCP, UDP 3COM Net Management - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2391, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2391'      # process listening on 2391
sudo lsof -nP -i :2391

macOS

sudo lsof -nP -i :2391

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2391 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2391
netstat -ano | findstr :2391

From another machine

nmap -p 2391 -sV <host>
sudo nmap -sU -p 2391 <host>
nc -zv <host> 2391

Block it in the firewall

sudo ufw deny 2391/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2391" -Direction Inbound -LocalPort 2391 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2391 used for?

Port 2391 is assigned by IANA to 3com-net-mgmt (3COM Net Management).

Is port 2391 TCP or UDP?

Port 2391 is registered for TCP and UDP.

Is it safe to open port 2391?

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 2391 is open?

On Linux run "ss -ltnup 'sport = :2391'", on macOS "lsof -nP -i :2391", and on Windows "netstat -ano | findstr :2391" to see the local process. From another machine, "nmap -p 2391 <host>" shows whether it is reachable.

05 Related
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