Справочник Пользователя для Netopia 4753 2a4na

In either case, the Netopia Router wraps, or encapsulates, information that one end of the tunnel 
exchanges with the other, in a wrapper called General Routing Encapsulation (GRE), at one end of the 
tunnel, and unwraps, or decapsulates, it at the other end.

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IPsec stands for IP Security, a set of protocols that suppor ts secure exchange of IP packets at the IP layer. 
IPsec is deployed widely to implement Vir tual Private Networks (VPNs). IPsec suppor ts two encr yption 
modes: Transpor t and Tunnel. Transpor t mode encr ypts only the data por tion (payload) of each packet, but 
leaves the header untouched. The more secure Tunnel mode encr ypts both the header and the payload. On 
the receiving side, an IPsec-compliant device decr ypts each packet. The Netopia 4753 suppor ts the more 
secure Tunnel mode.

DES stands for Data Encr yption Standard, a popular symmetric-key encr yption method. DES uses a 56-bit 
key. The Netopia 4753 offers IPsec DES encr yption over the VPN tunnel.

Configuring the Netopia Router for use with the different protocols is done through the console-based menu 
screens. Each type is described in its own section:

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Your configuration depends on which protocol you (and the router at the other end of your tunnel) will use, and 
whether or not you will be using the VPN client software in a standalone remote connection.

Having both an ATMP tunnel and a PPTP expor t is not possible because functions require GRE and the router’s 
PPTP expor t/ser ver does not distinguish the GRE packets it for wards. Since it processes all of them, ATMP 
tunneling is impaired. For example, you cannot run an ATMP tunnel between two routers and also have PPTP 
expor ted on one side.

A Vir tual Private Network (VPN) connects the components of one network over another network. VPNs 
accomplish this by allowing you to tunnel through the Internet or another public network in a manner that 
provides the same security and features formerly available only in private networks.

VPNs allow networks to communicate across an IP network. Your local networks (connected to the Netopia 
Router) can exchange data with remote networks that are also connected to a VPN-capable router.

This feature provides individuals at home, on the road, or in branch offices with a cost-effective and secure way 
to access resources on remote LANs connected to the Internet with Netopia Routers. The feature is built 
around three key technologies: PPTP, IPsec, and ATMP.

To set up a PPTP tunnel, you create a Connection Profile including the IP address and other relevant information 
for the remote PPTP par tner. You use the same procedure to initiate a PPTP tunnel that terminates at a remote 
PPTP ser ver or to terminate a tunnel initiated by a remote PPTP client.