CyberHunter
Local dataset, no network
// Other services

Port 6791: Halcyon Network Manager

Port 6791 is assigned by IANA to hnm (Halcyon Network Manager).

6791

How hnm works

Other services
client:6791hnmresponse client:6791hnmresponse

The client sends a request to port 6791 and the hnm 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 6791 dangerous?

We have no specific security note for port 6791. 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 6791

ServicePortTransportDescriptionReferenceUpdated
hnm 6791 TCP, UDP Halcyon Network Manager - 2023-05-24

// source: IANA service name and port number registry

03 Check it

Which program uses port 6791, and is it reachable?

Linux

sudo ss -ltnup 'sport = :6791'      # process listening on 6791
sudo lsof -nP -i :6791

macOS

sudo lsof -nP -i :6791

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6791 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 6791
netstat -ano | findstr :6791

From another machine

nmap -p 6791 -sV <host>
sudo nmap -sU -p 6791 <host>
nc -zv <host> 6791

Block it in the firewall

sudo ufw deny 6791/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 6791" -Direction Inbound -LocalPort 6791 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 6791 used for?

Port 6791 is assigned by IANA to hnm (Halcyon Network Manager).

Is port 6791 TCP or UDP?

Port 6791 is registered for TCP and UDP.

Is it safe to open port 6791?

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 6791 is open?

On Linux run "ss -ltnup 'sport = :6791'", on macOS "lsof -nP -i :6791", and on Windows "netstat -ano | findstr :6791" to see the local process. From another machine, "nmap -p 6791 <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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