Libnet is a high-level API (toolkit) allowing the application
programmer to construct and inject network packets. It provides a
portable and simplified interface for low-level network packet shaping,
handling and injection. Libnet hides much of the tedium of packet
creation from the application programmer such as multiplexing, buffer
management, arcane packet header information, byte-ordering,
OS-dependent issues, and much more. Libnet features portable packet
creation interfaces at both the IP-layer and link-layer, as well as a
host of supplementary and complementary functionality. Using libnet,
quick and simple packet assembly applications can be whipped up with
little effort. With a bit more time, more complex programs can be
written (Traceroute and Ping were easily rewritten using libnet and
libpcap).

Libnet is distrubuted under the BSD license.

Please note that at the time I wrote this SlackBuild script, libnet's
homepage (http://www.packetfactory.net/libnet/) was inaccessible for
some reason, so I pulled the source tarball from a gentoo mirror.
libnet.info reflects this. Check the homepage for a source code mirror
near you rather than use the gentoo tarball as I can't be certain how
often gentoo's mirrors are rearranged.

  -- Alan Hicks
     alan@lizella.net