/usr/bin/dumbnet-config is in libdumbnet-dev 1.12-7build1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | #!/bin/sh
#
# $Id: dumbnet-config.in 91 2001-10-19 01:29:00Z dugsong $
prefix=/usr
exec_prefix=/usr
usage()
{
	cat <<EOF
Usage: dumbnet-config [OPTIONS]
Options:
	[--version]
	[--libs]
	[--cflags]
EOF
	exit $1
}
if test $# -eq 0; then
	usage 1 1>&2
fi
while test $# -gt 0; do
  case "$1" in
  -*=*) optarg=`echo "$1" | sed 's/[-_a-zA-Z0-9]*=//'` ;;
  *) optarg= ;;
  esac
  case $1 in
    --version)
      echo 1.12
      ;;
    --cflags)
      echo_cflags=yes
      ;;
    --libs)
      echo_libs=yes
      ;;
    *)
      usage 1 1>&2
      ;;
  esac
  shift
done
if test "$echo_cflags" = "yes"; then
      echo -I${prefix}/include
fi
if test "$echo_libs" = "yes"; then
      echo -ldumbnet 
fi      
 |