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// Other services

Port 3784: BFD Control Protocol

Port 3784 is assigned by IANA to bfd-control (BFD Control Protocol).

3784

How bfd-control works

Other services
client:3784bfd-controlresponse client:3784bfd-controlresponse

The client sends a request to port 3784 and the bfd-control 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 3784 dangerous?

We have no specific security note for port 3784. 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 3784

ServicePortTransportDescriptionReferenceUpdated
bfd-control 3784 TCP, UDP BFD Control Protocol RFC 5881 -

// source: IANA service name and port number registry

03 Check it

Which program uses port 3784, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3784'      # process listening on 3784
sudo lsof -nP -i :3784

macOS

sudo lsof -nP -i :3784

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3784 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3784
netstat -ano | findstr :3784

From another machine

nmap -p 3784 -sV <host>
sudo nmap -sU -p 3784 <host>
nc -zv <host> 3784

Block it in the firewall

sudo ufw deny 3784/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3784" -Direction Inbound -LocalPort 3784 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3784 used for?

Port 3784 is assigned by IANA to bfd-control (BFD Control Protocol).

Is port 3784 TCP or UDP?

Port 3784 is registered for TCP and UDP.

Is it safe to open port 3784?

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 3784 is open?

On Linux run "ss -ltnup 'sport = :3784'", on macOS "lsof -nP -i :3784", and on Windows "netstat -ano | findstr :3784" to see the local process. From another machine, "nmap -p 3784 <host>" shows whether it is reachable.

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