CyberHunter
Local dataset, no network
// Other services

Port 5903: Flight & Flow Info for Collaborative Env

Port 5903 is assigned by IANA to ff-ice (Flight & Flow Info for Collaborative Env).

5903

How ff-ice works

Other services
client:5903ff-iceresponse client:5903ff-iceresponse

The client sends a request to port 5903 and the ff-ice service answers.

Transport
TCP · UDP · SCTP
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
Other services
01 Security

Is port 5903 dangerous?

We have no specific security note for port 5903. 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 5903

ServicePortTransportDescriptionReferenceUpdated
ff-ice 5903 TCP, UDP, SCTP Flight & Flow Info for Collaborative Env - 2022-06-03

// source: IANA service name and port number registry

03 Check it

Which program uses port 5903, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5903'      # process listening on 5903
sudo lsof -nP -i :5903

macOS

sudo lsof -nP -i :5903

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5903 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5903
netstat -ano | findstr :5903

From another machine

nmap -p 5903 -sV <host>
sudo nmap -sU -p 5903 <host>
nc -zv <host> 5903

Block it in the firewall

sudo ufw deny 5903/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5903" -Direction Inbound -LocalPort 5903 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 5903 used for?

Port 5903 is assigned by IANA to ff-ice (Flight & Flow Info for Collaborative Env).

Is port 5903 TCP or UDP?

Port 5903 is registered for TCP and UDP and SCTP.

Is it safe to open port 5903?

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 5903 is open?

On Linux run "ss -ltnup 'sport = :5903'", on macOS "lsof -nP -i :5903", and on Windows "netstat -ano | findstr :5903" to see the local process. From another machine, "nmap -p 5903 <host>" shows whether it is reachable.

05 Related
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp

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