You need to install the libpcap with header files. There are ready-made
packages for all major distributions. FreeBSD, Debian and SuSE call it
"libpcap-devel", OS-X users can try the "fink" project to get the library.

./configure
./make
./make install

check permissions for /var/db/echolot.mac.
copy ./scripts to /usr/local/bin or somewhere else and check the paths
in the scripts for propper work, (if you want to use them.)