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// Web

Port 3631: C&S Web Services Port

Port 3631 is assigned by IANA to cs-services (C&S Web Services Port).

3631

How cs-services works

Web
browser:3631cs-services browser:3631cs-services

A browser sends an HTTP request to port 3631 and the cs-services server sends the page back.

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
Web
01 Security

Is port 3631 dangerous?

We have no specific security note for port 3631. Its risk depends on the program actually listening on it. General advice for web services:

  • Serve it over HTTPS only and check the HTTP security headers.
  • Keep admin consoles and development servers off the Internet.
  • Patch the application server and remove default credentials and sample apps.
02 Registry

IANA registry entries for port 3631

ServicePortTransportDescriptionReferenceUpdated
cs-services 3631 TCP, UDP C&S Web Services Port - 2002-10

// source: IANA service name and port number registry

03 Check it

Which program uses port 3631, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3631'      # process listening on 3631
sudo lsof -nP -i :3631

macOS

sudo lsof -nP -i :3631

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3631 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3631
netstat -ano | findstr :3631

From another machine

nmap -p 3631 -sV <host>
sudo nmap -sU -p 3631 <host>
nc -zv <host> 3631

Block it in the firewall

sudo ufw deny 3631/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3631" -Direction Inbound -LocalPort 3631 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3631 used for?

Port 3631 is assigned by IANA to cs-services (C&S Web Services Port).

Is port 3631 TCP or UDP?

Port 3631 is registered for TCP and UDP.

Is it safe to open port 3631?

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. Serve it over HTTPS only and check the HTTP security headers.

How do I check if port 3631 is open?

On Linux run "ss -ltnup 'sport = :3631'", on macOS "lsof -nP -i :3631", and on Windows "netstat -ano | findstr :3631" to see the local process. From another machine, "nmap -p 3631 <host>" shows whether it is reachable.

05 Related

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