BIG-IP Discard Server

Problem this snippet solves:

This iRule oeprates in tandem with the TCP mblb profile, which is available starting in 10.x. The iRule code provides a "discard server". It accepts TCP segments, but simply discards them. It will, however, gracefully respond to a FIN. Why do this? It's useful for testing. BIG-IP can support a very large number of simultaneous connections, and a high data rate. This level of performance can be more difficult to achieve with a more conventional platform.

To begin, create a virtual server with no pool members. From tmsh, execute the following:

modify /ltm virtual < your_vs > profiles add { mblb }

Then, add the following iRule, and apply it to your VS:

Code :

when CLIENT_ACCEPTED {
    TCP::collect
}
when CLIENT_DATA {
    TCP::payload replace 0 [TCP::payload length] ""
    TCP::collect
}