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Port 8266 (espeasy-p2p)

IANA assigns port 8266 to espeasy-p2p: ESPeasy peer-2-peer communication.

Registered (user) port, 1024-49151 UDP

Port 8266 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
espeasy-p2p UDP ESPeasy peer-2-peer communication ESPeasy -

Registry dates for this port: registered 2018-11-28.

Check what is listening on port 8266

Linux: UDP 8266
sudo ss -ulnp 'sport = :8266'
Linux / macOS: which process owns the port
sudo lsof -nP -i :8266
Windows (Command Prompt)
netstat -ano | findstr :8266
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 8266

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 8266

Block port 8266 in the firewall

ufw
sudo ufw deny 8266/udp
iptables
sudo iptables -A INPUT -p udp --dport 8266 -j DROP
nftables
sudo nft add rule inet filter input udp dport 8266 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 8266' -Direction Inbound -Protocol UDP -LocalPort 8266 -Action Block

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