Wow. Just when I thought it couldn't get any better than rob_au's code (which looked great), you post this! I'm a little confused how this allows concurrent pings using threads when fork() doesn't appear to, but it's so much better than what I'm using now I just don't care.

Have just done a run of about 4500 machines. Timings:

That's about 26 times faster. I think I want to have your children ;)

And I think Ninthwave nearly wet himself as it's going to benefit a script he's writing at the moment to scan 14000+ machines!

Cheers,

Gordon.

P.S. I don't really actually want to have your children. Biological impossibility. You knew that, right? :)