well if it is a standard system utility that will be "grep" or "xargs" in Linux/Unix.
If you meant a security tool then that would be either netcat, or one of its derivatives "cryptocat, socat, linkcat,.etc"
Now for C&A I love the tool, <paranoia> however it is not open source, and i am wondering if enough security auditing is done on the tool itself, that is the tool can be used as a sniffer, and password cracker. that's a lot of parsing, and possibilities of buffer overflows. it is usually run as an admin, so any vurnability on it while using it could be disastrous </end paranoia>
I guess i will let it pass and chose metasploit for a security frame work.
for a security distro it will be BackTack, well i do consider it a utility
