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// Other services

Port 752:

Port 752 is assigned by IANA to qrh ().

752

How qrh works

Other services
client:752qrhresponse client:752qrhresponse

The client sends a request to port 752 and the qrh 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 752 dangerous?

We have no specific security note for port 752. 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 752

ServicePortTransportDescriptionReferenceUpdated
qrh 752 TCP, UDP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 752, and is it reachable?

Linux

sudo ss -ltnup 'sport = :752'      # process listening on 752
sudo lsof -nP -i :752

macOS

sudo lsof -nP -i :752

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 752 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 752
netstat -ano | findstr :752

From another machine

nmap -p 752 -sV <host>
sudo nmap -sU -p 752 <host>
nc -zv <host> 752

Block it in the firewall

sudo ufw deny 752/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 752" -Direction Inbound -LocalPort 752 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 752 used for?

Port 752 is assigned by IANA to qrh ().

Is port 752 TCP or UDP?

Port 752 is registered for TCP and UDP.

Is it safe to open port 752?

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 752 is open?

On Linux run "ss -ltnup 'sport = :752'", on macOS "lsof -nP -i :752", and on Windows "netstat -ano | findstr :752" to see the local process. From another machine, "nmap -p 752 <host>" shows whether it is reachable.

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