Appendix C - About VPNs
123
Common VPN Situations
VPN Pass-through
Figure 76: VPN Pass-through
Here, a PC on the LAN behind the Router/Gateway is using VPN software, but the
Router/Gateway is NOT acting as a VPN endpoint. It is only allowing the VPN connec-
tion.
• The PC software can use any VPN protocol supported by the remote VPN.
• The remote VPN Server must support client PCs which are behind a NAT router,
and so have an IP address which is not valid on the Internet.
• The Router/Gateway requires no VPN configuration, since it is not acting as a
VPN endpoint.
Client PC to VPN Gateway
Figure 77: Client PC to VPN Server
In this situation, the PC must run appropriate VPN client software in order to connect,
via the Internet, to the Wireless ADSL2/2+ Modem Router or other VPN Gateway.
Once connected, the client PC has the same access to LAN resources as PCs on the
local LAN (unless restricted by the network administrator).
• IPsec is not the only protocol which can be used in this situation, but the Wireless
ADSL2/2+ Modem Router supports IPsec ONLY.
• Windows 2000 and Windows XP include an IPsec VPN client program. However,
configuration of this client program for use with the Wireless ADSL2/2+ Modem
Router is very complex and beyond the scope of this document.
