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// Other services

Port 5543: QF-Test License Server / QF-Test MCP Server

Port 5543 is assigned by IANA to qftest-lic-mcp (QF-Test License Server / QF-Test MCP Server).

5543

How qftest-lic-mcp works

Other services
client:5543qftest-lic-mcpresponse client:5543qftest-lic-mcpresponse

The client sends a request to port 5543 and the qftest-lic-mcp service answers.

Transport
TCP
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 5543 dangerous?

We have no specific security note for port 5543. 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 5543

ServicePortTransportDescriptionReferenceUpdated
qftest-lic-mcp 5543 TCP QF-Test License Server / QF-Test MCP Server - 2026-09-04
-5543-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 5543, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5543'      # process listening on 5543
sudo lsof -nP -i :5543

macOS

sudo lsof -nP -i :5543

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5543 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5543
netstat -ano | findstr :5543

From another machine

nmap -p 5543 -sV <host>
nc -zv <host> 5543

Block it in the firewall

sudo ufw deny 5543/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5543" -Direction Inbound -LocalPort 5543 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 5543 used for?

Port 5543 is assigned by IANA to qftest-lic-mcp (QF-Test License Server / QF-Test MCP Server).

Is port 5543 TCP or UDP?

Port 5543 is registered for TCP.

Is it safe to open port 5543?

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 5543 is open?

On Linux run "ss -ltnup 'sport = :5543'", on macOS "lsof -nP -i :5543", and on Windows "netstat -ano | findstr :5543" to see the local process. From another machine, "nmap -p 5543 <host>" shows whether it is reachable.

05 Related
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