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Port 40853 (ortec-disc)

IANA assigns port 40853 to ortec-disc: ORTEC Service Discovery.

Registered (user) port, 1024-49151 UDP

Port 40853 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
ortec-disc UDP ORTEC Service Discovery Jesse Ursery -

Registry dates for this port: registered 2010-11-22.

Check what is listening on port 40853

Linux: UDP 40853
sudo ss -ulnp 'sport = :40853'
Linux / macOS: which process owns the port
sudo lsof -nP -i :40853
Windows (Command Prompt)
netstat -ano | findstr :40853
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 40853

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 40853

Block port 40853 in the firewall

ufw
sudo ufw deny 40853/udp
iptables
sudo iptables -A INPUT -p udp --dport 40853 -j DROP
nftables
sudo nft add rule inet filter input udp dport 40853 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 40853' -Direction Inbound -Protocol UDP -LocalPort 40853 -Action Block

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