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// Other services

Port 4803: Notateit Messaging

Port 4803 is assigned by IANA to notateit (Notateit Messaging), notateit-disc (Notateit Messaging Discovery).

4803

How notateit works

Other services
client:4803notateitresponse client:4803notateitresponse

The client sends a request to port 4803 and the notateit service answers.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned2 registered services
Range
Registered (1024-49151)
Category
Other services
01 Security

Is port 4803 dangerous?

We have no specific security note for port 4803. 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 4803

ServicePortTransportDescriptionReferenceUpdated
notateit 4803 TCP Notateit Messaging - -
notateit-disc 4803 UDP Notateit Messaging Discovery - 2009-04-08

// source: IANA service name and port number registry

03 Check it

Which program uses port 4803, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4803'      # process listening on 4803
sudo lsof -nP -i :4803

macOS

sudo lsof -nP -i :4803

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4803 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4803
netstat -ano | findstr :4803

From another machine

nmap -p 4803 -sV <host>
sudo nmap -sU -p 4803 <host>
nc -zv <host> 4803

Block it in the firewall

sudo ufw deny 4803/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4803" -Direction Inbound -LocalPort 4803 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4803 used for?

Port 4803 is assigned by IANA to notateit (Notateit Messaging), notateit-disc (Notateit Messaging Discovery).

Is port 4803 TCP or UDP?

Port 4803 is registered for TCP and UDP.

Is it safe to open port 4803?

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 4803 is open?

On Linux run "ss -ltnup 'sport = :4803'", on macOS "lsof -nP -i :4803", and on Windows "netstat -ano | findstr :4803" to see the local process. From another machine, "nmap -p 4803 <host>" shows whether it is reachable.

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