| When NetScaler application switch is used as L3+ switch, informations |
| regarding the original IP and TCP headers are lost as a new TCP |
| connection is created between the NetScaler and the backend server. |
| |
| NetScaler provides a feature to insert in the TCP data the original data |
| that can then be consumed by the backend server. |
| |
| Specifications and documentations from NetScaler: |
| https://support.citrix.com/article/CTX205670 |
| https://www.citrix.com/blogs/2016/04/25/how-to-enable-client-ip-in-tcpip-option-of-netscaler/ |
| |
| When CIP is enabled on the NetScaler, then a TCP packet is inserted just after |
| the TCP handshake. This is composed as: |
| |
| - CIP magic number : 4 bytes |
| Both sender and receiver have to agree on a magic number so that |
| they both handle the incoming data as a NetScaler Client IP insertion |
| packet. |
| |
| - Header length : 4 bytes |
| Defines the length on the remaining data. |
| |
| - IP header : >= 20 bytes if IPv4, 40 bytes if IPv6 |
| Contains the header of the last IP packet sent by the client during TCP |
| handshake. |
| |
| - TCP header : >= 20 bytes |
| Contains the header of the last TCP packet sent by the client during TCP |
| handshake. |