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// Other services

Port 4371: LAN2CAN Control

Port 4371 is assigned by IANA to l2c-control (LAN2CAN Control), l2c-disc (LAN2CAN Discovery).

4371

How l2c-control works

Other services
client:4371l2c-controlresponse client:4371l2c-controlresponse

The client sends a request to port 4371 and the l2c-control service answers.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned2 registered services
Range
Registered (1024-49151)
Category
Other services
01 Security

Is port 4371 dangerous?

We have no specific security note for port 4371. 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 4371

ServicePortTransportDescriptionReferenceUpdated
l2c-control 4371 TCP LAN2CAN Control - 2008-07-07
l2c-disc 4371 UDP LAN2CAN Discovery - 2010-01-21

// source: IANA service name and port number registry

03 Check it

Which program uses port 4371, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4371'      # process listening on 4371
sudo lsof -nP -i :4371

macOS

sudo lsof -nP -i :4371

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4371 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4371
netstat -ano | findstr :4371

From another machine

nmap -p 4371 -sV <host>
sudo nmap -sU -p 4371 <host>
nc -zv <host> 4371

Block it in the firewall

sudo ufw deny 4371/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4371" -Direction Inbound -LocalPort 4371 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4371 used for?

Port 4371 is assigned by IANA to l2c-control (LAN2CAN Control), l2c-disc (LAN2CAN Discovery).

Is port 4371 TCP or UDP?

Port 4371 is registered for TCP and UDP.

Is it safe to open port 4371?

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 4371 is open?

On Linux run "ss -ltnup 'sport = :4371'", on macOS "lsof -nP -i :4371", and on Windows "netstat -ano | findstr :4371" to see the local process. From another machine, "nmap -p 4371 <host>" shows whether it is reachable.

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