Autokey Keep Alive
Concentrator
Enable Autokey Keep Alive to keep the VPN tunnel running even if no data is being processed.
Select a concentrator if you want the tunnel to be part of a hub and spoke VPN configuration. If you use the procedure, Adding a VPN concentrator to add the tunnel to a concentrator, the next time you open the tunnel, the Concentrator field displays the name of the concentrator to which you have added the tunnel.
•Select OK to save the AutoIKE key VPN tunnel.
Adding an AutoIKE key VPN tunnel
About the P2 proposal
During tunnel negotiation, the VPN gateways negotiate to select a common algorithm for data communication. When you select algorithms for the P2 proposal, you are selecting the algorithms that the
•Select DES to propose to encrypt packets using DES encryption.
•Select 3DES to propose to encrypt packets using
•Select MD5 to propose to use MD5 authentication.
•Select SHA1 to propose to use SHA1 authentication.
•Select NULL to propose that the VPN packets not be encrypted or that a hash is not made for authentication.
About replay detection
IPSec tunnels can be vulnerable to replay attacks. A replay attack occurs when an unauthorized party intercepts a series of IPSec packets and replays them back into the tunnel. An attacker can use this technique to cause a denial of service (DoS) attack by flooding the tunnel with packets. An attacker could also change and then replay intercepted packets to attempt to gain entry to a trusted network.
Enable replay detection to check the sequence number of every IPSec packet to see if it has previously been received. If packets arrive out of sequence, the
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