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// Web

Port 3111: Web Synchronous Services

Port 3111 is assigned by IANA to wsynch (Web Synchronous Services).

3111

How wsynch works

Web
browser:3111wsynch browser:3111wsynch

A browser sends an HTTP request to port 3111 and the wsynch 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 3111 dangerous?

We have no specific security note for port 3111. 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 3111

ServicePortTransportDescriptionReferenceUpdated
wsynch 3111 TCP, UDP Web Synchronous Services - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 3111, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3111'      # process listening on 3111
sudo lsof -nP -i :3111

macOS

sudo lsof -nP -i :3111

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3111 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3111
netstat -ano | findstr :3111

From another machine

nmap -p 3111 -sV <host>
sudo nmap -sU -p 3111 <host>
nc -zv <host> 3111

Block it in the firewall

sudo ufw deny 3111/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3111" -Direction Inbound -LocalPort 3111 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3111 used for?

Port 3111 is assigned by IANA to wsynch (Web Synchronous Services).

Is port 3111 TCP or UDP?

Port 3111 is registered for TCP and UDP.

Is it safe to open port 3111?

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 3111 is open?

On Linux run "ss -ltnup 'sport = :3111'", on macOS "lsof -nP -i :3111", and on Windows "netstat -ano | findstr :3111" to see the local process. From another machine, "nmap -p 3111 <host>" shows whether it is reachable.

05 Related
:443 HTTPS tcp · udp · sctp · low risk :80 HTTP tcp · udp · sctp · moderate risk :8080 HTTP alternate tcp · udp · high risk :8443 HTTPS alternate tcp · udp · moderate risk :3000 Dev servers / Grafana tcp · udp · moderate risk :5000 Flask / Docker registry / UPnP tcp · udp · moderate risk :8000 HTTP alternate (dev) tcp · udp · moderate risk :8888 Jupyter / HTTP alternate tcp · udp · high risk

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