freebsd-src/share/examples/find_interface
Warner Losh 3bdf775801 NO_MAN= has been deprecated in favor of MAN= for some time, go ahead
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.
2014-04-13 05:21:56 +00:00
..
find_interface.c
Makefile
README

This is a simple program which demonstrates how to query the kernel
routing mechanism using only a UDP socket.  Pass it a hostname on
the command line (sorry, it doesn't parse dotted decimal) and it will
print out an IP address which names the interface over which UDP
packets intended for that destination would be sent.
A more sophisticated program might use the list obtained from SIOCGIFCONF
to match the address with an interface name, but applications programmers
much more often need to know the address of the interface rather than
the name.