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Port 4936 (an-signaling)

IANA assigns port 4936 to an-signaling: Signal protocol port for autonomic networking.

Registered (user) port, 1024-49151 UDP

Port 4936 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
an-signaling UDP Signal protocol port for autonomic networking Cisco Systems 3 -

Registry dates for this port: registered 2014-06-06.

Check what is listening on port 4936

Linux: UDP 4936
sudo ss -ulnp 'sport = :4936'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4936
Windows (Command Prompt)
netstat -ano | findstr :4936
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 4936

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4936

Block port 4936 in the firewall

ufw
sudo ufw deny 4936/udp
iptables
sudo iptables -A INPUT -p udp --dport 4936 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4936 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4936' -Direction Inbound -Protocol UDP -LocalPort 4936 -Action Block

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4915frcs4930fmsg4937atsc-mh-ssc4940eq-office-4940

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