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Port 10500 (hip-nat-t)

IANA assigns port 10500 to hip-nat-t: HIP NAT-Traversal.

Registered (user) port, 1024-49151 UDP

Port 10500 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
hip-nat-t UDP HIP NAT-Traversal IESG RFC 5770, RFC 9028

Registry dates for this port: last modified 2020-08-12.

Check what is listening on port 10500

Linux: UDP 10500
sudo ss -ulnp 'sport = :10500'
Linux / macOS: which process owns the port
sudo lsof -nP -i :10500
Windows (Command Prompt)
netstat -ano | findstr :10500
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 10500

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 10500

Block port 10500 in the firewall

ufw
sudo ufw deny 10500/udp
iptables
sudo iptables -A INPUT -p udp --dport 10500 -j DROP
nftables
sudo nft add rule inet filter input udp dport 10500 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 10500' -Direction Inbound -Protocol UDP -LocalPort 10500 -Action Block

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