网上下到的一个很详细介绍VPN基础知识的资料

				RCSID $Id: net.Config.in,v 1.5 1999/09/17 17:48:36 rgb Exp $				--- ./net/Config.in.preipsec	Mon Jul 13 16:47:40 1998				+++ ./net/Config.in	Thu Sep 16 11:26:31 1999				@@ -24,4 +24,8 @@				 if [ "$CONFIG_NETLINK" = "y" ]; then				   bool 'Routing messages' CONFIG_RTNETLINK				 fi				+tristate 'IP Security Protocol (FreeS/WAN IPSEC)' CONFIG_IPSEC				+if [ "$CONFIG_IPSEC" != "n" ]; then				+  source net/ipsec/Config.in				+fi				 endmenu