#!/bin/sh
#
paths="/sys /usr/include /usr/src/sys"
for i in ${paths}; do
    if [ -f $i/netinet/ip_nat.h ]; then
	exit 0
    fi
done
echo Unable find netinet/ip_nat.h
echo This header file from ipfilter package
echo Try to locate ip_nat.h and manually create links in following catalogs:
echo $paths
exit 1