CyberHunter
Local dataset, no network
// Other services

Port 133: Statistics Service

Port 133 is assigned by IANA to statsrv (Statistics Service).

133

How statsrv works

Other services
client:133statsrvresponse client:133statsrvresponse

The client sends a request to port 133 and the statsrv 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 133 dangerous?

We have no specific security note for port 133. 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 133

ServicePortTransportDescriptionReferenceUpdated
statsrv 133 TCP, UDP Statistics Service - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 133, and is it reachable?

Linux

sudo ss -ltnup 'sport = :133'      # process listening on 133
sudo lsof -nP -i :133

macOS

sudo lsof -nP -i :133

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 133 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 133
netstat -ano | findstr :133

From another machine

nmap -p 133 -sV <host>
sudo nmap -sU -p 133 <host>
nc -zv <host> 133

Block it in the firewall

sudo ufw deny 133/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 133" -Direction Inbound -LocalPort 133 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 133 used for?

Port 133 is assigned by IANA to statsrv (Statistics Service).

Is port 133 TCP or UDP?

Port 133 is registered for TCP and UDP.

Is it safe to open port 133?

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 133 is open?

On Linux run "ss -ltnup 'sport = :133'", on macOS "lsof -nP -i :133", and on Windows "netstat -ano | findstr :133" to see the local process. From another machine, "nmap -p 133 <host>" shows whether it is reachable.

05 Related
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