Port 34966 (profinet-rt-sec)

IANA assigns port 34966 to profinet-rt-sec: PROFINET secure real-time data transfer over UDP (unicast and multicast).

Registered (user) port, 1024-49151 UDP

Port 34966 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

profinet-rt-sec UDP PROFINET secure real-time data transfer over UDP (unicast and multicast) PNO PROFIBUS Nutzerorganisation e.V. -

Registry dates for this port: registered 2026-03-10.

Linux: UDP 34966

sudo ss -ulnp 'sport = :34966'

Linux / macOS: which process owns the port

sudo lsof -nP -i :34966

Windows (Command Prompt)

netstat -ano | findstr :34966

Windows (PowerShell)

Get-NetUDPEndpoint -LocalPort 34966

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 34966

ufw

sudo ufw deny 34966/udp

iptables

sudo iptables -A INPUT -p udp --dport 34966 -j DROP

nftables

sudo nft add rule inet filter input udp dport 34966 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 34966' -Direction Inbound -Protocol UDP -LocalPort 34966 -Action Block

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