ZyXEL Communications USG40 User Manual page 350

Table 144 Configuration > VPN > IPSec VPN > VPN Connection > Edit (continued)
LABEL DESCRIPTION
Active Protocol Select which protocol you want to use in the IPSec SA. Choices are:
AH (RFC 2402) - provides integrity, authentication, sequence integrity (replay
resistance), and non-repudiation but not encryption. If you select AH, you must
select an Authentication algorithm.
ESP (RFC 2406) - provides encryption and the same services offered by AH, but its
authentication is weaker. If you select ESP, you must select an Encryption algorithm
and Authentication algorithm.
Both AH and ESP increase processing requirements and latency (delay).
The ZyWALL/USG and remote IPSec router must use the same active protocol.
Encapsulation Select which type of encapsulation the IPSec SA uses. Choices are
Tunnel - this mode encrypts the IP header information and the data.
Transport - this mode only encrypts the data.
The ZyWALL/USG and remote IPSec router must use the same encapsulation.
Proposal Use this section to manage the encryption algorithm and authentication algorithm
pairs the ZyWALL/USG accepts from the remote IPSec router for negotiating the
IPSec SA.
Add Click this to create a new entry.
Edit Select an entry and click this to be able to modify it.
Remove Select an entry and click this to delete it.
# This field is a sequential value, and it is not associated with a specific proposal. The
sequence of proposals should not affect performance significantly.
Encryption This field is applicable when the Active Protocol is ESP. Select which key size and
encryption algorithm to use in the IPSec SA. Choices are:
NULL - no encryption key or algorithm
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/USG and the remote IPSec router must both have at least one proposal
that uses use the same encryption and the same key.
Longer keys are more secure, but require more processing power, resulting in
increased latency and decreased throughput.
Authentication 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 ZyWALL/USG and the remote IPSec router must both have a proposal that uses
the same authentication algorithm.
Chapter 19 IPSec VPN
ZyWALL/USG Series User's Guide
350