ZyXEL Communications 310 User Manual page 300

Chapter 20 IPSec VPN
Table 110 Configuration > VPN > IPSec VPN > VPN Gateway > Edit (continued)
LABEL
Encryption
Authentication
Key Group
NAT Traversal
Dead Peer
Detection (DPD)
More Settings/Less
Settings
Extended
Authentication
Enable Extended
Authentication
Server Mode
300
DESCRIPTION
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
AES192 - a 192-bit key with the AES encryption algorithm
AES256 - a 256-bit key with the AES encryption algorithm
The ZyWALL 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.
Select which hash algorithm to use to authenticate packet data in the IPSec SA.
Choices are SHA1, SHA256, SHA512 and MD5. SHA is generally considered stronger
than MD5, but it is also slower.
The remote IPSec router must use the same authentication algorithm.
Select which Diffie-Hellman key group (DHx) you want to use for encryption keys.
Choices are:
DH1 - use a 768-bit random number
DH2 - use a 1024-bit random number
DH5 - use a 1536-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.
Select this if any of these conditions are satisfied.
• This IKE SA might be used to negotiate IPSec SAs that use ESP as the active
protocol.
• There are one or more NAT routers between the ZyWALL and remote IPSec router,
and these routers do not support IPSec pass-thru or a similar feature.
The remote IPSec router must also enable NAT traversal, and the NAT routers have to
forward packets with UDP port 500 and UDP 4500 headers unchanged.
Select this check box if you want the ZyWALL to make sure the remote IPSec router is
there before it transmits data through the IKE SA. The remote IPSec router must
support DPD. If there has been no traffic for at least 15 seconds, the ZyWALL sends a
message to the remote IPSec router. If the remote IPSec router responds, the ZyWALL
transmits the data. If the remote IPSec router does not respond, the ZyWALL shuts
down the IKE SA.
If the remote IPSec router does not support DPD, see if you can use the VPN connection
connectivity check (see Section 20.2.1 on page
Click this button to show or hide the Extended Authentication fields.
When multiple IPSec routers use the same VPN tunnel to connect to a single VPN tunnel
(telecommuters sharing a tunnel for example), use extended authentication to enforce
a user name and password check. This way even though they all know the VPN tunnel's
security settings, each still has to provide a unique user name and password.
Select this if one of the routers (the ZyWALL or the remote IPSec router) verifies a user
name and password from the other router using the local user database and/or an
external server.
Select this if the ZyWALL authenticates the user name and password from the remote
IPSec router. You also have to select the authentication method, which specifies how
the ZyWALL authenticates this information.
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ZyWALL 110/310/1100 Series User's Guide