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Reference Manual for the ProSafe Wireless 802.11g Firewall/Print Server Model FWG114P v2
Virtual Private Networking F-9
201-10301-02, May 2005
Figure F-5: VPN Tunnel SA
The SA contains all the information necessary for gateway A to negotiate a secure and encrypted
communication stream with gateway B. This communication is often referred to as a “tunnel.” The
gateways contain this information so that it does not have to be loaded onto every computer
connected to the gateways.
Each gateway must negotiate its Security Association with another gateway using the parameters
and processes established by IPSec. As illustrated below, the most common method of
accomplishing this process is via the Internet Key Exchange (IKE) protocol which automates some
of the negotiation procedures. Alternatively, you can configure your gateways using manual key
exchange, which involves manually configuring each paramter on both gateways.
Figure F-6: IPSec SA negotiation
1. The IPSec software on Host A initiates the IPSec process in an attempt to communicate
with Host B. The two computers then begin the Internet Key Exchange (IKE) process.
A
B
VPN Gateway
VPN Gateway
1) Communication
request sent toVPN Gateway
2) IKE Phase I authentication
3) IKE Phase II negotiation
4) Secure data transfer
5) IPSec tunnel termination
IPSec Security Association IKE
VPN Tunnel Negotiation Steps