Requirements

System

Windows 10 or Windows 11 (x64)
~200 MB disk space
Connected to a local network or VPN with other ETSi users

Network

Port 9090 — P2P mesh listener (inbound + outbound)
Port 9095 — Direct peer chat
Port 9099 — Zero trust gateway proxy
Port 8080 — Caddy static web server (outbound only, when hosting)

All peers must be on the same subnet or reachable via a routed VPN for discovery to work. ETSi does not use broadcast or mDNS.

Firewall

You may need to allow ETSi through Windows Defender Firewall on first launch. ETSi will prompt for permission automatically. Ensure your corporate firewall or VPN policy permits traffic on the ports above between endpoints.