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// Other services

Port 1789: hello

Port 1789 is assigned by IANA to hello (hello).

1789

How hello works

Other services
client:1789helloresponse client:1789helloresponse

The client sends a request to port 1789 and the hello 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 1789 dangerous?

We have no specific security note for port 1789. 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 1789

ServicePortTransportDescriptionReferenceUpdated
hello 1789 TCP, UDP hello - 2018-04-05

// source: IANA service name and port number registry

03 Check it

Which program uses port 1789, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1789'      # process listening on 1789
sudo lsof -nP -i :1789

macOS

sudo lsof -nP -i :1789

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1789 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1789
netstat -ano | findstr :1789

From another machine

nmap -p 1789 -sV <host>
sudo nmap -sU -p 1789 <host>
nc -zv <host> 1789

Block it in the firewall

sudo ufw deny 1789/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1789" -Direction Inbound -LocalPort 1789 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1789 used for?

Port 1789 is assigned by IANA to hello (hello).

Is port 1789 TCP or UDP?

Port 1789 is registered for TCP and UDP.

Is it safe to open port 1789?

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 1789 is open?

On Linux run "ss -ltnup 'sport = :1789'", on macOS "lsof -nP -i :1789", and on Windows "netstat -ano | findstr :1789" to see the local process. From another machine, "nmap -p 1789 <host>" shows whether it is reachable.

05 Related
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