Wake-on-LAN Packet Builder

Build a Wake-on-LAN magic packet — and see why a browser cannot send it.

What you provide

The target's subnet broadcast, e.g. 192.168.1.255. A broadcast does not cross a router.

9 is conventional; 7 also works.

Result

102-byte magic packet for 00:1a:2b:3c:4d:5e

A magic packet is six bytes of 0xFF followed by the target MAC repeated exactly sixteen times — 102 bytes in total. The repetition is what makes it recognisable to a network card that is otherwise asleep and doing no protocol processing at all, which is also why the UDP port barely matters: the card matches on the payload pattern rather than on the port. This page builds the packet and cannot send it, because browsers have no access to raw UDP. Send it with wakeonlan, a router's built-in function, or PowerShell — and note it must reach the target's broadcast domain, since a broadcast does not cross a router by default.

Diagnostic telemetry
Packet sizeSix bytes of 0xFF, then the MAC repeated sixteen times.
102 bytes
Target MAC
00:1a:2b:3c:4d:5e
DestinationUDP. Port 9 is the usual choice; 7 also works. The port is not really used — the packet is matched by content.
255.255.255.255:9
Payload (hex)
ffffffffffff001a2b3c4d5e001a2b3c4d5e001a2b3c4d5e…
Sent from this pageBrowsers cannot send raw UDP. The packet is built here for you to send with a tool that can.
No

What this cannot tell you

  • Builds the packet and cannot send it. Browsers have no access to raw UDP, so no web page can wake a machine — one claiming to is either using a helper you installed or not doing what it says.
  • A magic packet is a broadcast and does not cross a router by default. It must originate inside the target's own broadcast domain unless the router is configured to forward it.
  • Wake-on-LAN must also be enabled in the target's firmware and network adapter settings. The packet arriving is not sufficient on its own.
  • Runs entirely in your browser. Nothing is looked up, transmitted or stored.

Take this with you

Wake-on-LAN Packet Builder on RunTheTests — free browser-based sysadmin tools, no sign-up.