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Port 4412 (smallchat)

IANA assigns port 4412 to smallchat: SmallChat.

Registered (user) port, 1024-49151 UDP

Port 4412 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

IANA assignment

Service nameProtoDescriptionAssigneeReference
smallchat UDP SmallChat Valentino Giudice -

Registry dates for this port: registered 2015-08-18.

Check what is listening on port 4412

Linux: UDP 4412
sudo ss -ulnp 'sport = :4412'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4412
Windows (Command Prompt)
netstat -ano | findstr :4412
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 4412

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4412

Block port 4412 in the firewall

ufw
sudo ufw deny 4412/udp
iptables
sudo iptables -A INPUT -p udp --dport 4412 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4412 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4412' -Direction Inbound -Protocol UDP -LocalPort 4412 -Action Block

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All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.