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// Other services

Port 5556: Freeciv gameplay

Port 5556 is assigned by IANA to freeciv (Freeciv gameplay).

5556

How freeciv works

Other services
client:5556freecivresponse client:5556freecivresponse

The client sends a request to port 5556 and the freeciv service answers.

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
Other services
01 Security

Is port 5556 dangerous?

We have no specific security note for port 5556. 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 5556

ServicePortTransportDescriptionReferenceUpdated
freeciv 5556 TCP, UDP Freeciv gameplay
Reported: Known Unauthorized Use on port 5556
 - 2006-01

// source: IANA service name and port number registry

03 Check it

Which program uses port 5556, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5556'      # process listening on 5556
sudo lsof -nP -i :5556

macOS

sudo lsof -nP -i :5556

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5556 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5556
netstat -ano | findstr :5556

From another machine

nmap -p 5556 -sV <host>
sudo nmap -sU -p 5556 <host>
nc -zv <host> 5556

Block it in the firewall

sudo ufw deny 5556/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5556" -Direction Inbound -LocalPort 5556 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 5556 used for?

Port 5556 is assigned by IANA to freeciv (Freeciv gameplay).

Is port 5556 TCP or UDP?

Port 5556 is registered for TCP and UDP.

Is it safe to open port 5556?

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 5556 is open?

On Linux run "ss -ltnup 'sport = :5556'", on macOS "lsof -nP -i :5556", and on Windows "netstat -ano | findstr :5556" to see the local process. From another machine, "nmap -p 5556 <host>" shows whether it is reachable.

05 Related
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