CyberHunter
Local dataset, no network
// Other services

Port 3991: BindView-SMCServer

Port 3991 is assigned by IANA to bv-smcsrv (BindView-SMCServer).

3991

How bv-smcsrv works

Other services
client:3991bv-smcsrvresponse client:3991bv-smcsrvresponse

The client sends a request to port 3991 and the bv-smcsrv 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 3991 dangerous?

We have no specific security note for port 3991. 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 3991

ServicePortTransportDescriptionReferenceUpdated
bv-smcsrv 3991 TCP, UDP BindView-SMCServer - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 3991, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3991'      # process listening on 3991
sudo lsof -nP -i :3991

macOS

sudo lsof -nP -i :3991

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3991 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3991
netstat -ano | findstr :3991

From another machine

nmap -p 3991 -sV <host>
sudo nmap -sU -p 3991 <host>
nc -zv <host> 3991

Block it in the firewall

sudo ufw deny 3991/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3991" -Direction Inbound -LocalPort 3991 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3991 used for?

Port 3991 is assigned by IANA to bv-smcsrv (BindView-SMCServer).

Is port 3991 TCP or UDP?

Port 3991 is registered for TCP and UDP.

Is it safe to open port 3991?

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 3991 is open?

On Linux run "ss -ltnup 'sport = :3991'", on macOS "lsof -nP -i :3991", and on Windows "netstat -ano | findstr :3991" to see the local process. From another machine, "nmap -p 3991 <host>" shows whether it is reachable.

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