Proscend 6200-2W, User Manual, Page: 63 / 93

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A VPN (Virtual Private Network) provides a secure connection between 2 points, over an insecure network. The Secure
is called a VPN Tunnel.
The VPN Router supports three main type of VPN: IPsec, L2TP and PPTP.
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IPsec is a near-ubiquitous VPN security standard, designed for use with TCP/IP networks. It works at the packet level,
and authenticates and encrypts all packets traveling over the VPN Tunnel. Thus, it does not matter what applications
are used on your PC. Any application can use the VPN like any other network connection.
IPsec VPNs exchange information through logical connections called SAs(Security Associations). An SA is simply a
definition of the protocols, algorithms and keys used between the two VPN devices(endpoints)
There are two security modes possible with IPsec:
Transport Mode – the payload (data) part of the packet is encapsulated through encryption but the IP header remains
in the clear (unchanged)
Tunnel Mode – everything is encapsulated including the original IP header, and a new IP header is generated. Only the
new header in the clear (i.e. not protected). This system provides enhanced security.
IKE(Interface Key Exchange) is an optional, but widely used, component of IPsec.
IKE provides a method of negotiating and generating the keys and IDs required by IPsec. If using IKE, only a single key is
required to be provided during configuration. Also, IKE supports using Certificates to authenticate the identify of the
remote user or gateway.
If IKE is not used, then all keys and IDs(SPIs) must be entered manually, and Certificates can’t be used, This is called a
“Manual Key Exchange”.