CyberHunter
Local dataset, no network
// Other services

Port 2840: l3-exprt

Port 2840 is assigned by IANA to l3-exprt (l3-exprt).

2840

How l3-exprt works

Other services
client:2840l3-exprtresponse client:2840l3-exprtresponse

The client sends a request to port 2840 and the l3-exprt 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 2840 dangerous?

We have no specific security note for port 2840. 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 2840

ServicePortTransportDescriptionReferenceUpdated
l3-exprt 2840 TCP, UDP l3-exprt - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2840, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2840'      # process listening on 2840
sudo lsof -nP -i :2840

macOS

sudo lsof -nP -i :2840

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2840 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2840
netstat -ano | findstr :2840

From another machine

nmap -p 2840 -sV <host>
sudo nmap -sU -p 2840 <host>
nc -zv <host> 2840

Block it in the firewall

sudo ufw deny 2840/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2840" -Direction Inbound -LocalPort 2840 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2840 used for?

Port 2840 is assigned by IANA to l3-exprt (l3-exprt).

Is port 2840 TCP or UDP?

Port 2840 is registered for TCP and UDP.

Is it safe to open port 2840?

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 2840 is open?

On Linux run "ss -ltnup 'sport = :2840'", on macOS "lsof -nP -i :2840", and on Windows "netstat -ano | findstr :2840" to see the local process. From another machine, "nmap -p 2840 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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