ZyXEL P-202H User Guide - Page 132

Manual Key

Page 132 highlights

P-202H Plus v2 User's Guide Table 38 Advanced Rule Setup (continued) LABEL Encryption Algorithm Authentication Algorithm SA Life Time Encapsulation Perfect Forward Secrecy (PFS) Apply Cancel DESCRIPTION The encryption algorithm for the ZyXEL Device and the secure remote gateway should be identical. When DES is used for data communications, both sender and receiver must know the same secret key, which can be used to encrypt and decrypt the message or to generate and verify a message authentication code. The DES encryption algorithm uses a 56-bit key. Triple DES (3DES) is a variation on DES that uses a 168-bit key. As a result, 3DES is more secure than DES. It also requires more processing power, resulting in increased latency and decreased throughput. Select NULL to set up a tunnel without encryption. When you select NULL, you do not enter an encryption key. Select SHA1 or MD5 from the drop-down list box. MD5 (Message Digest 5) and SHA1 (Secure Hash Algorithm) are hash algorithms used to authenticate packet data. The SHA1 algorithm is generally considered stronger than MD5, but is slower. Select MD5 for minimal security and SHA-1 for maximum security. Define the length of time before an IKE SA automatically renegotiates in this field. It may range from 60 to 3,000,000 seconds (almost 35 days). 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. Select Tunnel mode or Transport mode from the drop down list-box. The ZyXEL Device's encapsulation mode should be identical to the secure remote gateway. Perfect Forward Secrecy (PFS) is disabled (None) by default in phase 2 IPSec SA setup. This allows faster IPSec setup, but is not so secure. Choose from DH1 or DH2 to enable PFS. DH1 refers to Diffie-Hellman Group 1, a 768 bit random number. DH2 refers to Diffie-Hellman Group 2, a 1024 bit (1Kb) random number (more secure, yet slower). Click Apply to save your changes back to the ZyXEL Device and return to the VPN-IKE screen. Click Cancel to return to the VPN-IKE screen without saving your ZyXEL Device. 11.12 Manual Key Manual key management is useful if you have problems with IKE key management. 11.12.1 Security Parameter Index (SPI) An SPI is used to distinguish different SAs terminating at the same destination and using the same IPSec protocol. This data allows for the multiplexing of SAs to a single gateway. The SPI (Security Parameter Index) along with a destination IP address uniquely identify a particular Security Association (SA). The SPI is transmitted from the remote VPN gateway to the local VPN gateway. The local VPN gateway then uses the network, encryption and key values that the administrator associated with the SPI to establish the tunnel. Note: Current ZyXEL implementation assumes identical outgoing and incoming SPIs. 131 Chapter 11 VPN Screens

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P-202H Plus v2 User’s Guide
131
Chapter 11 VPN Screens
11.12
Manual Key
Manual key management is useful if you have problems with
IKE
key management.
11.12.1
Security Parameter Index (SPI)
An SPI is used to distinguish different SAs terminating at the same destination and using the
same IPSec protocol. This data allows for the multiplexing of SAs to a single gateway. The
SPI
(Security Parameter Index) along with a destination IP address uniquely identify a
particular Security Association (SA). The
SPI
is transmitted from the remote VPN gateway to
the local VPN gateway. The local VPN gateway then uses the network, encryption and key
values that the administrator associated with the SPI to establish the tunnel.
Note:
Current ZyXEL implementation assumes identical outgoing and incoming SPIs.
Encryption Algorithm
The encryption algorithm for the ZyXEL Device and the secure remote
gateway should be identical.
When
DES
is used for data communications, both sender and receiver must
know the same secret key, which can be used to encrypt and decrypt the
message or to generate and verify a message authentication code. The
DES
encryption algorithm uses a 56-bit key. Triple DES (
3DES
) is a variation on
DES
that uses a 168-bit key. As a result,
3DES
is more secure than
DES
. It
also requires more processing power, resulting in increased latency and
decreased throughput. Select
NULL
to set up a tunnel without encryption.
When you select
NULL
, you do not enter an encryption key.
Authentication
Algorithm
Select
SHA1
or
MD5
from the drop-down list box. MD5 (Message Digest 5)
and SHA1 (Secure Hash Algorithm) are hash algorithms used to authenticate
packet data. The SHA1 algorithm is generally considered stronger than MD5,
but is slower. Select
MD5
for minimal security and
SHA-1
for maximum
security.
SA Life Time
Define the length of time before an IKE SA automatically renegotiates in this
field. It may range from 60 to 3,000,000 seconds (almost 35 days).
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.
Encapsulation
Select
Tunnel
mode or
Transport
mode from the drop down list-box. The
ZyXEL Device's encapsulation mode should be identical to the secure remote
gateway.
Perfect Forward
Secrecy (PFS)
Perfect Forward Secrecy (PFS) is disabled (None) by default in phase 2 IPSec
SA setup. This allows faster IPSec setup, but is not so secure. Choose from
DH1
or
DH2
to enable PFS.
DH1
refers to Diffie-Hellman Group 1, a 768 bit
random number.
DH2
refers to Diffie-Hellman Group 2, a 1024 bit (1Kb)
random number (more secure, yet slower).
Apply
Click
Apply
to save your changes back to the ZyXEL Device and return to the
VPN-IKE
screen.
Cancel
Click
Cancel
to return to the
VPN-IKE
screen without saving your ZyXEL
Device.
Table 38
Advanced Rule Setup (continued)
LABEL
DESCRIPTION