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// Network services

Port 4133: NUTS Bootp Server

Port 4133 is assigned by IANA to nuts_bootp (NUTS Bootp Server), nuts-bootp (NUTS Bootp Server IANA assigned this well-formed service name as a replacement for "nuts_bootp".).

4133

How nuts_bootp works

Network services
client:4133nuts_bootpresponse client:4133nuts_bootpresponse

The client sends a request to port 4133 and the nuts_bootp service answers.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned2 registered services
Range
Registered (1024-49151)
Category
Network services
01 Security

Is port 4133 dangerous?

We have no specific security note for port 4133. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 4133

ServicePortTransportDescriptionReferenceUpdated
nuts_bootp 4133 TCP, UDP NUTS Bootp Server - -
nuts-bootp 4133 TCP, UDP NUTS Bootp Server IANA assigned this well-formed service name as a replacement for "nuts_bootp". - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 4133, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4133'      # process listening on 4133
sudo lsof -nP -i :4133

macOS

sudo lsof -nP -i :4133

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4133 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4133
netstat -ano | findstr :4133

From another machine

nmap -p 4133 -sV <host>
sudo nmap -sU -p 4133 <host>
nc -zv <host> 4133

Block it in the firewall

sudo ufw deny 4133/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4133" -Direction Inbound -LocalPort 4133 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4133 used for?

Port 4133 is assigned by IANA to nuts_bootp (NUTS Bootp Server), nuts-bootp (NUTS Bootp Server IANA assigned this well-formed service name as a replacement for "nuts_bootp".).

Is port 4133 TCP or UDP?

Port 4133 is registered for TCP and UDP.

Is it safe to open port 4133?

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. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 4133 is open?

On Linux run "ss -ltnup 'sport = :4133'", on macOS "lsof -nP -i :4133", and on Windows "netstat -ano | findstr :4133" to see the local process. From another machine, "nmap -p 4133 <host>" shows whether it is reachable.

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