Microsoft VPN

IKE Phase 2 Screen

This screen sets the parameters for the IPSec SA. When using IKE, there are separate connections (SAs) for IKE and IPSec.

Figure56: VPN Wizard - IKE Phase 2 ScreenIKE Phase 2 (IPsec SA)
IPsec SA Life Time

This setting does not have to match the remote VPN endpoint; the

 

shorter time will be used. Although measured in seconds, it is

 

common to use time periods of several hours, such 28,800 seconds.

 

 

IPSec PFS

If enabled, PFS (Perfect Forward Security) enhances security by

 

changing the IPsec key at regular intervals, and ensuring that each

 

key has no relationship to the previous key. Thus, breaking 1 key

 

will not assist in breaking the next key.

 

 

AH Authentication

AH (Authentication Header) specifies the authentication protocol

 

for the VPN header, if used.

 

AH is often NOT used. If you do enable it, ensure the algorithm

 

selected matches the other VPN endpoint.

 

 

ESP Encryption

ESP (Encapsulating Security Payload) provides security for the

 

payload (data) sent through the VPN tunnel. Generally, you will

 

want to enable both ESP Encryption and ESP Authentication.

Select the desired method, and ensure the remote VPN endpoint uses the same method.

∙The 3DES algorithm provides greater security than DES, but is slower.

∙If using AES, you must select the Key Size. If using DES or 3DES, this field is ignored.

ESP Authentication Generally, you should enable ESP Authentication. There is little difference between the available algorithms. Just ensure each endpoint use the same setting.

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