Add a test for ICMP fragmentation needed DOS attack

Please add a test with ICMP fragmentation needed DOS attack. The test would create a TCP or UDP connection, and send a lot of such ICMP with different MTUs to IUT referring this connection. At the end the test should ensure that the connection is still usable. In a sense, the test would be similar to attacks/icmp/icmp_flood.

Iterations:

TCP or UDP;
different ranges for MTU in ICMPs: "limited" within 576 - 1500; "unlimited" 0 - 0xffff.

Any additions to the test scenario are welcome.

NB in https://github.com/Xilinx-CNS/onload ci_ipp_pmtu_rx() I read:

  /* hardly a worth-while dos attack, however ... */
  /* ... (proof that i'm not great at predictions) by april 2005 it was picked
   *  up by the media as part of a world-spanning problem :-) */

Xilinx-CNS / cns-sapi-ts

Add a test for ICMP fragmentation needed DOS attack #83