Hping

Hping is a security analysis tool that allows the user to craft his/her own packets. It's an easy port AFAICT, I got it to compile though it got an error when it tried to send data (ip_send: bad something-or-other)

http://www.hping.org/

I've just got hping2 working on OS X
I had to edit configure and getifname.c - I'll sort out some diffs and post a link shortly.

here's my steps to get hping2-rc2 working on osx.
libpcap may be a requirement(?) - I've got it installed, through fink.

download http://www.hping.org/hping2.0.0-rc2.tar.gz
extract it
download patch http://www.raik.demon.co.uk/lawnjam/hping2-osx.diff
cd hping2-rc2
patch < hping2-osx.diff
./configure
make
make strip

enjoy!