网上下到的一个很详细介绍VPN基础知识的资料

				#!/bin/bash				#				# RCSID $Id: kernel.patch.gen.sh,v 1.4 1999/04/06 04:54:30 rgb Exp $								patchdir=`pwd`				kernelsrc=/usr/src/linux				[ "$1~" = "~" ] || kernelsrc=$1				cd $kernelsrc				# clean out destination file for all patch				#echo "">$patchdir/all								# find files to patch and loop				for i in  `find . -name '*.preipsec'`				do								# strip off '.preipsec' suffix				j=${i%.preipsec}								# strip off './' prefix				k=${j#\.\/}								# single unified diff				#diff -u $i $j >>$patchdir/all								# convert '/' in filename to '.' to avoid subdirectories				sed -e 's/\//\./g'  /tmp/t				$k				EOI				l=`cat /tmp/t`				rm -f /tmp/t								# *with* path from source root				#echo do diff -u $i $j '>' $patchdir/$l				echo found $i				echo "RCSID \$Id: kernel.patch.gen.sh,v 1.4 1999/04/06 04:54:30 rgb Exp $" >$patchdir/$l				diff -u $i $j >>$patchdir/$l								done								#				# $Log: kernel.patch.gen.sh,v $				# Revision 1.4  1999/04/06 04:54:30  rgb				# Fix/Add RCSID Id: and Log: bits to make PHMDs happy.  This includes				# patch shell fixes.				#				#