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Port 8981 (nod-client)

IANA assigns port 8981 to nod-client: Network of Devices Client.

Registered (user) port, 1024-49151 UDP

Port 8981 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
nod-client UDP Network of Devices Client David Muller -

Registry dates for this port: registered 2015-02-22.

Check what is listening on port 8981

Linux: UDP 8981
sudo ss -ulnp 'sport = :8981'
Linux / macOS: which process owns the port
sudo lsof -nP -i :8981
Windows (Command Prompt)
netstat -ano | findstr :8981
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 8981

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 8981

Block port 8981 in the firewall

ufw
sudo ufw deny 8981/udp
iptables
sudo iptables -A INPUT -p udp --dport 8981 -j DROP
nftables
sudo nft add rule inet filter input udp dport 8981 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 8981' -Direction Inbound -Protocol UDP -LocalPort 8981 -Action Block

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