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// Other services

Port 633: Service Status update (Sterling Software)

Port 633 is assigned by IANA to servstat (Service Status update (Sterling Software)).

633

How servstat works

Other services
client:633servstatresponse client:633servstatresponse

The client sends a request to port 633 and the servstat 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 633 dangerous?

We have no specific security note for port 633. 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 633

ServicePortTransportDescriptionReferenceUpdated
servstat 633 TCP, UDP Service Status update (Sterling Software) - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 633, and is it reachable?

Linux

sudo ss -ltnup 'sport = :633'      # process listening on 633
sudo lsof -nP -i :633

macOS

sudo lsof -nP -i :633

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 633 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 633
netstat -ano | findstr :633

From another machine

nmap -p 633 -sV <host>
sudo nmap -sU -p 633 <host>
nc -zv <host> 633

Block it in the firewall

sudo ufw deny 633/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 633" -Direction Inbound -LocalPort 633 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 633 used for?

Port 633 is assigned by IANA to servstat (Service Status update (Sterling Software)).

Is port 633 TCP or UDP?

Port 633 is registered for TCP and UDP.

Is it safe to open port 633?

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 633 is open?

On Linux run "ss -ltnup 'sport = :633'", on macOS "lsof -nP -i :633", and on Windows "netstat -ano | findstr :633" to see the local process. From another machine, "nmap -p 633 <host>" shows whether it is reachable.

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