Go

Currently running this bitch on a server with 24 processors clocked at 2.6Ghz, 16GB of ram and fiber connection. Currently pinging about 300-400 IP addresses/second. And the glue holding this bitch together is Go. Look at that simple concurrency model and message passing, it's a thing of fucking beauty. Now to get this running on the other 4 servers just like it.

http://pastebin.com/rqEvpszX
Currently running at: 177 valid IPs/second, 582 IPs/second

And I know that the last part is a little hacky and that the IP functions should be moved to their own source file. Bite me.

Why aren't you using Go /prog/?

main = sequence_ $ parMap rseq createProcess
       [proc "ping" . (["-c", "2", "-i", "0.2", "-w", "1"] ++) . (:[]) . intercalate "." . map show $
        [a,b,c,d] | a <- [0..255], b <- [0..255], c <- [0..255], d <- [0..255]]