Virtual Private Networks (VPNs) 11-1CCCChhhhaaaapppptttteeeerrrr 11111111VVVViiiirrrrttttuuuuaaaallll PPPPrrrriiiivvvvaaaatttteeee NNNNeeeettttwwwwoooorrrrkkkkssss ((((VVVVPPPPNNNNssss))))The Netopia 4741 offers IPsec, PPTP, and ATMP tunneling support for Virtual Private Networks (VPN).The following topics are covered in this chapter: Overview on page 11-1 About PPTP Tunnels on page 11-3 About IPsec Tunnels on page 11-7 Encryption Support on page 11-12 ATMP/PPTP Default Answer Profile on page 11-13 VPN QuickView on page 11-14 Dial-Up Networking for VPN on page 11-15 About ATMP Tunnels on page 11-19 Allowing VPNs through a Firewall on page 11-21OverviewWhen you make a long distance telephone call from your home to a relative far away, you are creating a privatenetwork. You can hold a conversation, and exchange information about the happenings on opposite sides of thestate, or the continent, that you are mutually interested in. When your next door neighbor picks up the phone tocall her daughter at college, at the same time you are talking to your relatives, your calls don't overlap, but eachis separate and private. Neither house has a direct wire to the places they call. Both share the same lines onthe telephone poles (or underground) on the street.These calls are virtual private networks. Virtual, because they appear to be direct connections between thecalling and answering parties, even though they travel over the public wires and switches of the phonecompany; private, because neither pair of calling and answering parties interacts with the other; and networks,because they exchange information.Computers can do the same thing; it's called Virtual Private Networks (VPNs). Equipped with a Netopia 4741, asingle computer or private network (LAN) can establish a private connection with another computer or privatenetwork over the public network (Internet).The Netopia 4741 can be used in VPNs either to initiate the connection or to answer it. When used in this way,the routers are said to be tunnelling through the public network (Internet). The advantages are that, like yourlong distance phone call, you don't need a direct line between one computer or LAN and the other, but use thelocal connections, making it much cheaper; and the information you exchange through your tunnel is private andsecure.
