The Citrix Netscaler has an interesting property that embeds information in the TCP packet that gets sent to the host. This property is echoed back to the Netscaler in such a way that the Netscaler can use this to determine which Virtual Server, host, and route this must take.
The ability to echo proprietary information to a host has interesting applications.
How does the Citrix Netscaler achieve this (where does it stuff the bits), and what other locations in the packet can the Netscaler (or similar device) theoretically stuff data?
What devices will (or will not) allow this custom data to pass through untouched?