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// Other services

Port 2723: WatchDog NT Protocol

Port 2723 is assigned by IANA to watchdog-nt (WatchDog NT Protocol).

2723

How watchdog-nt works

Other services
client:2723watchdog-ntresponse client:2723watchdog-ntresponse

The client sends a request to port 2723 and the watchdog-nt 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 2723 dangerous?

We have no specific security note for port 2723. 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 2723

ServicePortTransportDescriptionReferenceUpdated
watchdog-nt 2723 TCP, UDP WatchDog NT Protocol - 2020-07-20

// source: IANA service name and port number registry

03 Check it

Which program uses port 2723, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2723'      # process listening on 2723
sudo lsof -nP -i :2723

macOS

sudo lsof -nP -i :2723

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2723 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2723
netstat -ano | findstr :2723

From another machine

nmap -p 2723 -sV <host>
sudo nmap -sU -p 2723 <host>
nc -zv <host> 2723

Block it in the firewall

sudo ufw deny 2723/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2723" -Direction Inbound -LocalPort 2723 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2723 used for?

Port 2723 is assigned by IANA to watchdog-nt (WatchDog NT Protocol).

Is port 2723 TCP or UDP?

Port 2723 is registered for TCP and UDP.

Is it safe to open port 2723?

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 2723 is open?

On Linux run "ss -ltnup 'sport = :2723'", on macOS "lsof -nP -i :2723", and on Windows "netstat -ano | findstr :2723" to see the local process. From another machine, "nmap -p 2723 <host>" shows whether it is reachable.

05 Related
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