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// Other services

Port 3966: BuildForge Lock Manager

Port 3966 is assigned by IANA to bflckmgr (BuildForge Lock Manager).

3966

How bflckmgr works

Other services
client:3966bflckmgrresponse client:3966bflckmgrresponse

The client sends a request to port 3966 and the bflckmgr 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 3966 dangerous?

We have no specific security note for port 3966. 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 3966

ServicePortTransportDescriptionReferenceUpdated
bflckmgr 3966 TCP, UDP BuildForge Lock Manager - 2005-08

// source: IANA service name and port number registry

03 Check it

Which program uses port 3966, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3966'      # process listening on 3966
sudo lsof -nP -i :3966

macOS

sudo lsof -nP -i :3966

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3966 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3966
netstat -ano | findstr :3966

From another machine

nmap -p 3966 -sV <host>
sudo nmap -sU -p 3966 <host>
nc -zv <host> 3966

Block it in the firewall

sudo ufw deny 3966/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3966" -Direction Inbound -LocalPort 3966 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3966 used for?

Port 3966 is assigned by IANA to bflckmgr (BuildForge Lock Manager).

Is port 3966 TCP or UDP?

Port 3966 is registered for TCP and UDP.

Is it safe to open port 3966?

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 3966 is open?

On Linux run "ss -ltnup 'sport = :3966'", on macOS "lsof -nP -i :3966", and on Windows "netstat -ano | findstr :3966" to see the local process. From another machine, "nmap -p 3966 <host>" shows whether it is reachable.

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