CyberHunter
Local dataset, no network
// Other services

Port 16309: etb4j

Port 16309 is assigned by IANA to etb4j (etb4j).

16309

How etb4j works

Other services
client:16309etb4jresponse client:16309etb4jresponse

The client sends a request to port 16309 and the etb4j 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 16309 dangerous?

We have no specific security note for port 16309. 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 16309

ServicePortTransportDescriptionReferenceUpdated
etb4j 16309 TCP, UDP etb4j - 2004-11

// source: IANA service name and port number registry

03 Check it

Which program uses port 16309, and is it reachable?

Linux

sudo ss -ltnup 'sport = :16309'      # process listening on 16309
sudo lsof -nP -i :16309

macOS

sudo lsof -nP -i :16309

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 16309 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 16309
netstat -ano | findstr :16309

From another machine

nmap -p 16309 -sV <host>
sudo nmap -sU -p 16309 <host>
nc -zv <host> 16309

Block it in the firewall

sudo ufw deny 16309/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 16309" -Direction Inbound -LocalPort 16309 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 16309 used for?

Port 16309 is assigned by IANA to etb4j (etb4j).

Is port 16309 TCP or UDP?

Port 16309 is registered for TCP and UDP.

Is it safe to open port 16309?

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 16309 is open?

On Linux run "ss -ltnup 'sport = :16309'", on macOS "lsof -nP -i :16309", and on Windows "netstat -ano | findstr :16309" to see the local process. From another machine, "nmap -p 16309 <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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