From: Peter Zijlstra <redacted>
Date: Sat, 12 Aug 2006 12:18:07 +0200

65535 sockets * 128 packets * 16384 bytes/packet = 
1^16 * 1^7 * 1^14 = 1^(16+7+14) = 1^37 = 128G of memory per IP

And systems with a lot of IP numbers are not unthinkable.

TCP restricts the amount of global memory that may be consumed
by all TCP sockets via the tcp_mem[] sysctl.

Otherwise several forms of DoS attacks would be possible.