This is a fast TFTP config filename bruteforcer written for "Hacking Exposed: Cisco Networks". 
It uses multiple parallel connections for maximum efficiency. Be reasonable, since if TFTPd is 
run from Xinetd, it will cut on the amount of allowed connections to the server. Also, add the
config names to the list to suit your needs, a usual dictionary file would do, but it is better
to take into account hostnames of the server box and routers it may serve the config files to.
If you want to snatch an IOS from the server, fingerprint the routers first to make intelligent
filename guesses.