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// Other services

Port 3543: qftest Lookup Port

Port 3543 is assigned by IANA to qftest-lookup (qftest Lookup Port).

3543

How qftest-lookup works

Other services
client:3543qftest-lookupresponse client:3543qftest-lookupresponse

The client sends a request to port 3543 and the qftest-lookup 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 3543 dangerous?

We have no specific security note for port 3543. 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 3543

ServicePortTransportDescriptionReferenceUpdated
qftest-lookup 3543 TCP, UDP qftest Lookup Port - 2002-07

// source: IANA service name and port number registry

03 Check it

Which program uses port 3543, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3543'      # process listening on 3543
sudo lsof -nP -i :3543

macOS

sudo lsof -nP -i :3543

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3543 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3543
netstat -ano | findstr :3543

From another machine

nmap -p 3543 -sV <host>
sudo nmap -sU -p 3543 <host>
nc -zv <host> 3543

Block it in the firewall

sudo ufw deny 3543/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3543" -Direction Inbound -LocalPort 3543 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3543 used for?

Port 3543 is assigned by IANA to qftest-lookup (qftest Lookup Port).

Is port 3543 TCP or UDP?

Port 3543 is registered for TCP and UDP.

Is it safe to open port 3543?

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 3543 is open?

On Linux run "ss -ltnup 'sport = :3543'", on macOS "lsof -nP -i :3543", and on Windows "netstat -ano | findstr :3543" to see the local process. From another machine, "nmap -p 3543 <host>" shows whether it is reachable.

05 Related
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