Port 3702 (WS-Discovery)

Web Services Dynamic Discovery, used by Windows network discovery, printers and ONVIF cameras.

Registered (user) port, 1024-49151 UDP Network infrastructure Localhost or LAN only

Port 3702 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

What port 3702 is used for

Web Services Dynamic Discovery, used by Windows network discovery, printers and ONVIF cameras.

Localhost or LAN only. Exposed WS-Discovery devices are used for large DDoS amplification; block at the perimeter.

Service nameProtoDescriptionAssigneeReference

ws-discovery TCP Web Service Discovery Christian Huitema 2 -

ws-discovery UDP Web Service Discovery Christian Huitema 2 -

Registry dates for this port: registered 2003-02.

Linux: UDP 3702

sudo ss -ulnp 'sport = :3702'

Linux / macOS: which process owns the port

sudo lsof -nP -i :3702

Windows (Command Prompt)

netstat -ano | findstr :3702

Windows (PowerShell)

Get-NetUDPEndpoint -LocalPort 3702

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

nc -vzu -w 5 HOST 3702

ufw

sudo ufw deny 3702/udp

iptables

sudo iptables -A INPUT -p udp --dport 3702 -j DROP

nftables

sudo nft add rule inet filter input udp dport 3702 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 3702' -Direction Inbound -Protocol UDP -LocalPort 3702 -Action Block

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