> Could even go a lower level and use something like the TCP packets metadata as the encoding. Send data in the form of TTL variations across packets. Even bet

> Could even go a lower level and use something like the TCP packets metadata as the encoding. Send data in the form of TTL variations across packets. Even better: put it in the ICMP echo request; then you can also spoof the sending address if you wish. Or encode it in a DNS request/response.