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// Monitoring & logging

Port 3203: Network Watcher Monitor

Port 3203 is assigned by IANA to netwatcher-mon (Network Watcher Monitor).

3203

How netwatcher-mon works

Monitoring & logging
monitoringdevicenetwatcher-mon monitoringdevicenetwatcher-mon

The monitoring server collects metrics, alerts or logs from devices over port 3203.

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
Monitoring & logging
01 Security

Is port 3203 dangerous?

We have no specific security note for port 3203. Its risk depends on the program actually listening on it. General advice for monitoring & logging services:

  • Restrict management and monitoring protocols to the monitoring network.
  • Replace community strings and default credentials.
  • Send logs over TLS.
02 Registry

IANA registry entries for port 3203

ServicePortTransportDescriptionReferenceUpdated
netwatcher-mon 3203 TCP, UDP Network Watcher Monitor - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 3203, and is it reachable?

Linux

sudo ss -ltnup 'sport = :3203'      # process listening on 3203
sudo lsof -nP -i :3203

macOS

sudo lsof -nP -i :3203

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3203 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 3203
netstat -ano | findstr :3203

From another machine

nmap -p 3203 -sV <host>
sudo nmap -sU -p 3203 <host>
nc -zv <host> 3203

Block it in the firewall

sudo ufw deny 3203/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 3203" -Direction Inbound -LocalPort 3203 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 3203 used for?

Port 3203 is assigned by IANA to netwatcher-mon (Network Watcher Monitor).

Is port 3203 TCP or UDP?

Port 3203 is registered for TCP and UDP.

Is it safe to open port 3203?

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. Restrict management and monitoring protocols to the monitoring network.

How do I check if port 3203 is open?

On Linux run "ss -ltnup 'sport = :3203'", on macOS "lsof -nP -i :3203", and on Windows "netstat -ano | findstr :3203" to see the local process. From another machine, "nmap -p 3203 <host>" shows whether it is reachable.

05 Related
:161 SNMP udp · tcp · high risk :162 SNMP trap udp · tcp · moderate risk :9090 Prometheus / admin consoles tcp · udp · high risk :514 Syslog udp · tcp · moderate risk :6514 Syslog over TLS tcp · udp · dccp · low risk :5601 Kibana tcp · udp · high risk :391 SynOptics SNMP Relay Port tcp · udp :412 Trap Convention Port tcp · udp

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