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Port 3680 (npds-tracker)

IANA assigns port 3680 to npds-tracker: NPDS Tracker.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
npds-tracker TCP NPDS Tracker Paul Guyot -
npds-tracker UDP NPDS Tracker Paul Guyot -

Registry dates for this port: registered 2003-01.

Check what is listening on port 3680

Linux: is anything listening on TCP 3680?
sudo ss -tlnp 'sport = :3680'
Linux: UDP 3680
sudo ss -ulnp 'sport = :3680'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3680
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3680 '
Windows (Command Prompt)
netstat -ano | findstr :3680
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3680 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3680
From Windows
Test-NetConnection HOST -Port 3680
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3680

Block port 3680 in the firewall

ufw
sudo ufw deny 3680/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3680 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3680 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3680' -Direction Inbound -Protocol TCP -LocalPort 3680 -Action Block
ufw
sudo ufw deny 3680/udp
iptables
sudo iptables -A INPUT -p udp --dport 3680 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3680 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3680' -Direction Inbound -Protocol UDP -LocalPort 3680 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.