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Port 4361 (nacnl)

IANA assigns port 4361 to nacnl: NavCom Discovery and Control Port.

Registered (user) port, 1024-49151 UDP

Port 4361 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
nacnl UDP NavCom Discovery and Control Port Yilei Jia -

Registry dates for this port: registered 2009-03-18.

Check what is listening on port 4361

Linux: UDP 4361
sudo ss -ulnp 'sport = :4361'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4361
Windows (Command Prompt)
netstat -ano | findstr :4361
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 4361

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4361

Block port 4361 in the firewall

ufw
sudo ufw deny 4361/udp
iptables
sudo iptables -A INPUT -p udp --dport 4361 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4361 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4361' -Direction Inbound -Protocol UDP -LocalPort 4361 -Action Block

Related ports

4359omabcastltkm4360matrix-vnet, matrix_vnet4362afore-vdp-disc4366shadowstream

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