ZyXEL Communications Internet Security Gateway ZyWALL 2 Series - Manual (Page 232)

ZyWALL 2 Series User’s Guide
14-26 VPN Screens
Table 14-8 Advanced IKE VPN Rule Setup
LABEL DESCRIPTION
Enable Replay
Detection As a VPN setup is processing intensive, the system is vulnerable to Denial of Service
(DoS) attacks The IPSec receiver can detect and reject old or duplicate packets to protect
against replay attacks. Select YES from the drop-down menu to enable replay detection,
or select NO to disable it.
Local Port
Start "0" is the default and signifies any port. Type a port number from 0 to 65535. Some of the
most common IP ports are: 21, FTP; 53, DNS; 23, Telnet; 80, HTTP; 25, SMTP; 110,
POP3.
End Type a port number in this field to define a port range. This port number must be greater
than that specified in the previous field. If Local Port Start is left at 0, Local Port End will
also remain at 0.
Remote Port
Start Type up to 32 characters to identify this VPN policy. You may use any character, including
spaces, but the ZyWALL drops trailing spaces.
End Enter a port number in this field to define a port range. This port number must be greater
than that specified in the previous field. If Remote Port Start is left at 0, Remote Port
End will also remain at 0.
Phase 1
Negotiation Mode Select Main or Aggressive from the drop-down list box. Multiple SAs connecting through
a secure gateway must have the same negotiation mode.
Encryption
Algorithm
Select DES, 3DES or AES from the drop-down list box.
When you use one of these encryption algorithms for data communications, both the
sending device and the receiving device must use 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. This implementation of AES uses a 128-bit key. AES is faster than 3DES.