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// Other services

Port 3843: Quest Common Agent

Port 3843 is assigned by IANA to quest-agent (Quest Common Agent).

3843

How quest-agent works

Other services
client:3843quest-agentresponse client:3843quest-agentresponse

The client sends a request to port 3843 and the quest-agent 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 3843 dangerous?

We have no specific security note for port 3843. 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 3843

ServicePortTransportDescriptionReferenceUpdated
quest-agent 3843 TCP, UDP Quest Common Agent - 2003-11

// source: IANA service name and port number registry

03 Check it

Which program uses port 3843, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3843'      # process listening on 3843
sudo lsof -nP -i :3843

macOS

sudo lsof -nP -i :3843

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3843 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3843
netstat -ano | findstr :3843

From another machine

nmap -p 3843 -sV <host>
sudo nmap -sU -p 3843 <host>
nc -zv <host> 3843

Block it in the firewall

sudo ufw deny 3843/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3843" -Direction Inbound -LocalPort 3843 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3843 used for?

Port 3843 is assigned by IANA to quest-agent (Quest Common Agent).

Is port 3843 TCP or UDP?

Port 3843 is registered for TCP and UDP.

Is it safe to open port 3843?

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 3843 is open?

On Linux run "ss -ltnup 'sport = :3843'", on macOS "lsof -nP -i :3843", and on Windows "netstat -ano | findstr :3843" to see the local process. From another machine, "nmap -p 3843 <host>" shows whether it is reachable.

05 Related
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