CyberHunter
Local dataset, no network
// Other services

Port 1133: Data Flow Network

Port 1133 is assigned by IANA to dfn (Data Flow Network).

1133

How dfn works

Other services
client:1133dfnresponse client:1133dfnresponse

The client sends a request to port 1133 and the dfn 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 1133 dangerous?

We have no specific security note for port 1133. 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 1133

ServicePortTransportDescriptionReferenceUpdated
dfn 1133 TCP, UDP Data Flow Network - 2021-03-04

// source: IANA service name and port number registry

03 Check it

Which program uses port 1133, and is it reachable?

Linux

sudo ss -ltnup 'sport = :1133'      # process listening on 1133
sudo lsof -nP -i :1133

macOS

sudo lsof -nP -i :1133

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 1133 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 1133
netstat -ano | findstr :1133

From another machine

nmap -p 1133 -sV <host>
sudo nmap -sU -p 1133 <host>
nc -zv <host> 1133

Block it in the firewall

sudo ufw deny 1133/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 1133" -Direction Inbound -LocalPort 1133 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 1133 used for?

Port 1133 is assigned by IANA to dfn (Data Flow Network).

Is port 1133 TCP or UDP?

Port 1133 is registered for TCP and UDP.

Is it safe to open port 1133?

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 1133 is open?

On Linux run "ss -ltnup 'sport = :1133'", on macOS "lsof -nP -i :1133", and on Windows "netstat -ano | findstr :1133" to see the local process. From another machine, "nmap -p 1133 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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