Intro

Fun way to send a small bit of data via a relay host who doesn't know who you are (at least, not at the IP level).

Implementation

This is done by constructing a SYN packet, with the payload data in the sequence number (decremented by one). It is sent to the relay server, with the source address equal to the address of the destination. The relay server increments the sequence number, and does its part of the three-way handshake by sending an ACK back to the "source".

sender --- SYN ---> relay
(relay believes this SYN came from 'destination')
relay  --- ACK ---> destination

Usage

shadow -a (relay host) -s (destination) -p (port) -t "message"
shadowd -t (port)

Must be run as root, as it uses raw sockets.

Download

This code has no useful application whatsoever. Try not to use it. Your computer will probably explode.
Download here