How many IP address aliases can practically be used on one physical Ethernet interface?

[Crispy Beef]

Chuck Swiger wrote:
  > Use BPF or libnet to generate test traffic using spoofed IPs, rather than
> actually configuring a machine with thousands of IPs.  There are also companies
> which make hardware IP traffic generators, if you want to buy a solution rather
> than building one.

Have done a quick search on these and found the docs for libnet, can't seem to 
find much on BPF.

I could really do with a solution for testing a server under heavy load, I'm 
aware of the mod for Apache (flood I think) but I don't have the option of 
using that right now.  Would one of the above allow me to simulate multiple - 
hundreds or thousands - clients accessing a server?

The main reason is that I've recompiled apache to up the hard limit of 
MaxClients, the machine has 2Gb or RAM so should be able to handle plenty of 
connections but I'd like to see at what point it would fall over.

--
Cheers,

Paul