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Port 3702 · UDP

Port 3702: WS-Discovery

Web Services Dynamic Discovery, how Windows finds network printers, scanners and other PCs, over multicast.

Protocol
UDP
On Windows
svchost.exe (Function Discovery, fdPHost and FDResPub)
Risk if open to the internet
High

Seeing it on your PC

svchost.exe on 3702 with network discovery turned on.

Should you block it?

Local network only. Exposed WS-Discovery has been abused to amplify denial-of-service attacks.

Check it on your PC

Run this in PowerShell to see what is using port 3702 right now, and which program owns it:

Get-NetUDPEndpoint -LocalPort 3702 -ErrorAction SilentlyContinue | Select-Object LocalAddress,LocalPort,@{n='Process';e={(Get-Process -Id $_.OwningProcess -ErrorAction SilentlyContinue).ProcessName}}

No output means nothing is using the port at the moment. For every connection at once, paste netstat -ano into the netstat explainer.

Block it in Windows Firewall

In PowerShell run as administrator, this stops other computers from connecting to this port on your PC. It does not stop your own programs connecting out.

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

Undo it with Remove-NetFirewallRule -DisplayName "Block inbound …", using the same name. If you depend on the service on your local network, this rule stops that too.