ZyXEL Communications FMG3024-D10A Manual De Usuario

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Chapter 17 VPN
FMG3024-D10A / FMG3025-D10A Series User’s Guide
172
Authentication 
Algorithm
Select which hash algorithm to use to authenticate packet data. Choices are 
MD5SHA1SHA2-256 and SHA2-512SHA is generally considered stronger 
than MD5, but it is also slower.
DH
Select which Diffie-Hellman key group you want to use for encryption keys. 
Choices are:
Diffie-Hellman Group2 - use a 1024-bit random number
Diffie-Hellman Group5 - use a 1536-bit random number
Diffie-Hellman Group14 - use a 2048-bit random number
The longer the key, the more secure the encryption, but also the longer it takes 
to encrypt and decrypt information. Both routers must use the same DH key 
group.
SA Life Time
Define the length of time before an IPSec SA automatically renegotiates in this 
field.
A short SA Life Time increases security by forcing the two VPN gateways to 
update the encryption and authentication keys. However, every time the VPN 
tunnel renegotiates, all users accessing remote resources are temporarily 
disconnected. 
Phase 2
Encryption 
Algorithm
Select which key size and encryption algorithm to use in the IKE SA. Choices 
are:
DES - a 56-bit key with the DES encryption algorithm
3DES - a 168-bit key with the DES encryption algorithm
AES128 - a 128-bit key with the AES encryption algorithm
AES256 - a 256-bit key with the AES encryption algorithm
The Device and the remote IPSec router must use the same key size and 
encryption algorithm. Longer keys require more processing power, resulting in 
increased latency and decreased throughput.
Authentication 
Algorithm
Select which hash algorithm to use to authenticate packet data. Choices are 
MD5SHA1SHA is generally considered stronger than MD5, but it is also 
slower.
SA Life Time
Define the length of time before an IPSec SA automatically renegotiates in this 
field.
A short SA Life Time increases security by forcing the two VPN gateways to 
update the encryption and authentication keys. However, every time the VPN 
tunnel renegotiates, all users accessing remote resources are temporarily 
disconnected. 
Table 51   
IPSec VPN: Add
LABEL
DESCRIPTION