CyberHunter
Local dataset, no network
// Other services

Port 2739: TN Timing

Port 2739 is assigned by IANA to tn-timing (TN Timing).

2739

How tn-timing works

Other services
client:2739tn-timingresponse client:2739tn-timingresponse

The client sends a request to port 2739 and the tn-timing 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 2739 dangerous?

We have no specific security note for port 2739. 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 2739

ServicePortTransportDescriptionReferenceUpdated
tn-timing 2739 TCP, UDP TN Timing - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2739, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2739'      # process listening on 2739
sudo lsof -nP -i :2739

macOS

sudo lsof -nP -i :2739

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2739 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2739
netstat -ano | findstr :2739

From another machine

nmap -p 2739 -sV <host>
sudo nmap -sU -p 2739 <host>
nc -zv <host> 2739

Block it in the firewall

sudo ufw deny 2739/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2739" -Direction Inbound -LocalPort 2739 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2739 used for?

Port 2739 is assigned by IANA to tn-timing (TN Timing).

Is port 2739 TCP or UDP?

Port 2739 is registered for TCP and UDP.

Is it safe to open port 2739?

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 2739 is open?

On Linux run "ss -ltnup 'sport = :2739'", on macOS "lsof -nP -i :2739", and on Windows "netstat -ano | findstr :2739" to see the local process. From another machine, "nmap -p 2739 <host>" shows whether it is reachable.

05 Related
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